[doc] Update "Get Started" page for ORT web (#19568)

### Description
This PR re-arranges documentation of ORT web.

Current doc: https://onnxruntime.ai/docs/
Change preview: https://fs-eire.github.io/onnxruntime/docs/

- split `Doc -> Get Started -> JavaScript` from single page into
multiple pages, to make it easier to split from web, node and
react-native
- remove `Doc -> Get Started -> with Web`. The page was a few links and
now they are moved to other places
- add a few contents into `Doc -> Get Started -> JavaScript -> Web`. Now
this is the main page for ORT web doc.
- rename `Tutorials -> deploy on Web` to `Tutorials -> Web`. "deploy" is
confusing as it's not the accurate term to describe the content.

=================================================================


### Discussions:
TBD


=================================================================


### ORT web documentation work item list:

- [ ] Update `Get Started` page for ORT web at onnxruntime.ai **( this
PR )**
    - to make it easier for users to navigate
- [ ] Update `Tutorials` page for ORT web at onnxruntime.ai
- The purpose of this page is unclear. It contains descriptive
information and step-by-step instructions on an E2E examples. It can be
a good Blog, but not good for documentation, which usually has a
well-structured content.
- The [index
page](https://fs-eire.github.io/onnxruntime/docs/tutorials/web/) has
duplicated contents with its child page ["Build a web application with
ONNX
Runtime"](https://fs-eire.github.io/onnxruntime/docs/tutorials/web/build-web-app.html)
    - Some contents are out-of-dated.
- [ ] Update [`API Usage -
SessionOptions`](https://github.com/microsoft/onnxruntime-inference-examples/tree/main/js/api-usage_session-options)
on onnxruntime-inference-examples repo.
- Add explaination and examples if necessary for all new WebGPU session
options.
- [ ] Update [`API usage - ort.env
flags`](https://github.com/microsoft/onnxruntime-inference-examples/blob/main/js/api-usage_ort-env-flags)
on onnxruntime-inference-examples repo.
    - Add all newly introduced flags.

docs/get-started/training-on-device.md

@@ -1,7 +1,7 @@
 ---
 title: On-Device Training
 parent: Get Started
-nav_order: 12
+nav_order: 11
 ---
 
 # On-Device Training with ONNX Runtime

docs/get-started/with-javascript/index.md

@@ -0,0 +1,21 @@
+---
+title: JavaScript
+parent: Get Started
+has_children: true
+toc: false
+nav_order: 6
+---
+
+# Get started with ORT for JavaScript
+{: .no_toc }
+
+ONNX Runtime JavaScript API is the unified interface used by [ONNX Runtime Node.js binding](https://github.com/microsoft/onnxruntime/tree/main/js/node), [ONNX Runtime Web](https://github.com/microsoft/onnxruntime/tree/main/js/web), and [ONNX Runtime for React Native](https://github.com/microsoft/onnxruntime/tree/main/js/react_native).
+
+See [how to choose the right package](../../tutorials/web/build-web-app#options-for-deployment-target) for your JavaScript application.
+
+## Contents
+{: .no_toc }
+
+* Get Started with [ONNX Runtime Web](web.md)
+* Get Started with [ONNX Runtime Node.js binding](node.md)
+* Get Started with [ONNX Runtime for React Native](react-native.md)

docs/get-started/with-javascript/node.md

@@ -0,0 +1,54 @@
+---
+title: Node.js binding
+parent: JavaScript
+grand_parent: Get Started
+has_children: false
+nav_order: 2
+---
+
+# Get started with ONNX Runtime Node.js binding
+
+## Contents
+{: .no_toc }
+
+* TOC placeholder
+{:toc}
+
+## Install
+
+```bash
+# install latest release version
+npm install onnxruntime-node
+```
+
+## Import
+
+```js
+// use ES6 style import syntax (recommended)
+import * as ort from 'onnxruntime-node';
+```
+```js
+// or use CommonJS style import syntax
+const ort = require('onnxruntime-node');
+```
+
+## Examples
+
+- Follow the [Quick Start](https://github.com/microsoft/onnxruntime-inference-examples/tree/main/js/quick-start_onnxruntime-node) instructions for ONNX Runtime Node.js binding.
+
+## Supported Versions
+
+The following table lists the supported versions of ONNX Runtime Node.js binding provided with pre-built binaries.
+
+
+| EPs/Platforms | Windows x64 | Windows arm64 | Linux x64 | Linux arm64 | MacOS x64 | MacOS arm64 |
+|--------------|--------|---------|--------|------|---|----|
+| CPU  |   ✔️    |    ✔️    |   ✔️   |  ✔️  |  ✔️  |  ✔️  |
+| DirectML  |   ✔️    |    ✔️    |  ❌  |  ❌  |  ❌  |  ❌  |
+| CUDA     |  ❌  |  ❌  |  ✔️<sup>\[1]</sup>  | ❌ | ❌ |  ❌  |
+
+
+- \[1]: CUDA v11.8.
+
+
+For platforms not on the list or want a custom build, you can [build Node.js binding from source](../../build/inferencing.md#apis-and-language-bindings) and consume using `npm install <onnxruntime_repo_root>/js/node/`.

docs/get-started/with-javascript/react-native.md

@@ -0,0 +1,46 @@
+---
+title: React Native
+parent: JavaScript
+grand_parent: Get Started
+has_children: false
+nav_order: 3
+---
+
+# Get started with ONNX Runtime for React Native
+
+## Contents
+{: .no_toc }
+
+* TOC placeholder
+{:toc}
+
+
+## Install
+
+
+```bash
+# install latest release version
+npm install onnxruntime-react-native
+```
+
+## Import
+
+
+```js
+// use ES6 style import syntax (recommended)
+import * as ort from 'onnxruntime-react-native';
+```
+```js
+// or use CommonJS style import syntax
+const ort = require('onnxruntime-react-native');
+```
+
+
+### Enable ONNX Runtime Extensions for React Native
+To enable support for [ONNX Runtime Extensions](https://github.com/microsoft/onnxruntime-extensions) in your React Native app,
+you need to specify the following configuration as a top-level entry (note: usually where the package `name`and `version`fields are) in your project's root directory `package.json` file. 
+
+```js
+"onnxruntimeExtensionsEnabled": "true"
+```
+

docs/get-started/with-javascript/web.md

@@ -0,0 +1,101 @@
+---
+title: Web
+parent: JavaScript
+grand_parent: Get Started
+has_children: false
+nav_order: 1
+---
+
+# Get started with ONNX Runtime Web
+
+## Contents
+{: .no_toc }
+
+* TOC placeholder
+{:toc}
+
+## Install
+
+Use the following command in shell to install ONNX Runtime Web:
+
+```bash
+# install latest release version
+npm install onnxruntime-web
+
+# install nightly build dev version
+npm install onnxruntime-web@dev
+```
+
+## Import
+
+Use the following JavaScript code to import ONNX Runtime Web:
+
+```js
+// use ES6 style import syntax (recommended)
+import * as ort from 'onnxruntime-web';
+```
+```js
+// or use CommonJS style import syntax
+const ort = require('onnxruntime-web');
+```
+
+If you want to use ONNX Runtime Web with WebGPU support (experimental feature), you need to import as below:
+
+```js
+// use ES6 style import syntax (recommended)
+import * as ort from 'onnxruntime-web/webgpu';
+```
+```js
+// or use CommonJS style import syntax
+const ort = require('onnxruntime-web/webgpu');
+```
+
+For a complete table for importing, see [Conditional Importing](https://github.com/microsoft/onnxruntime-inference-examples/tree/main/js/importing_onnxruntime-web#conditional-importing).
+
+## Documentation
+
+See [ONNX Runtime JavaScript API](../../api/js/index.html){:target="_blank"} for API reference. Please also check the following links for API usage examples:
+- [Tensor](https://github.com/microsoft/onnxruntime-inference-examples/blob/main/js/api-usage_tensor) - a demonstration of basic usage of Tensor.
+- [Tensor <--> Image conversion](https://github.com/microsoft/onnxruntime-inference-examples/blob/main/js/api-usage-tensor-image) - a demonstration of conversions from Image elements to and from Tensor.
+- [InferenceSession](https://github.com/microsoft/onnxruntime-inference-examples/blob/main/js/api-usage_inference-session) - a demonstration of basic usage of InferenceSession.
+- [SessionOptions](https://github.com/microsoft/onnxruntime-inference-examples/blob/main/js/api-usage_session-options) - a demonstration of how to configure creation of an InferenceSession instance.
+- [ort.env flags](https://github.com/microsoft/onnxruntime-inference-examples/blob/main/js/api-usage_ort-env-flags) - a demonstration of how to configure a set of global flags.
+
+- See also: Typescript declarations for [Inference Session](https://github.com/microsoft/onnxruntime/blob/main/js/common/lib/inference-session.ts), [Tensor](https://github.com/microsoft/onnxruntime/blob/main/js/common/lib/tensor.ts), and [Environment Flags](https://github.com/microsoft/onnxruntime/blob/main/js/common/lib/env.ts) for reference.
+
+See [Tutorial: Web](../../tutorials/web/index.md) for tutorials.
+
+See [Training on web demo](https://github.com/microsoft/onnxruntime-training-examples/tree/master/on_device_training/web) for training using onnxruntime-web.
+
+## Examples
+
+The following examples describe how to use ONNX Runtime Web in your web applications for model inferencing:
+- [Quick Start (using bundler)](https://github.com/microsoft/onnxruntime-inference-examples/tree/main/js/quick-start_onnxruntime-web-bundler)
+- [Quick Start (using script tag)](https://github.com/microsoft/onnxruntime-inference-examples/tree/main/js/quick-start_onnxruntime-web-script-tag)
+
+The following are E2E examples that uses ONNX Runtime Web in web applications:
+- [Classify images with ONNX Runtime Web](https://onnxruntime.ai/docs/tutorials/web/classify-images-nextjs-github-template.html) - a simple web application using Next.js for image classifying.
+- [ONNX Runtime Web demos](https://microsoft.github.io/onnxruntime-web-demo/#/) for image recognition, handwriting analysis, real-time emotion detection, object detection, and so on.
+- [OpenAI Whisper](https://github.com/microsoft/onnxruntime-inference-examples/blob/main/js/ort-whisper) - demonstrates how to run [whisper tiny.en](https://github.com/openai/whisper) in your browser using onnxruntime-web and the browser's audio interfaces.
+- [Facebook Segment-Anything](https://github.com/microsoft/onnxruntime-inference-examples/blob/main/js/segment-anything) - demonstrates how to run [segment-anything](https://github.com/facebookresearch/segment-anything) in your browser using onnxruntime-web with webgpu.
+
+
+The following are video tutorials that use ONNX Runtime Web in web applications:
+- [ONNX Runtime Web for In Browser Inference](https://youtu.be/0dskvE4IvGM)
+- [Inference in Javascript with ONNX Runtime Web](https://youtu.be/vYzWrT3A7wQ)
+
+
+## Supported Versions
+
+| EPs/Browsers | Chrome/Edge (Windows) | Chrome/Edge (Android) | Chrome/Edge (MacOS) | Chrome/Edge (iOS) | Safari (MacOS) | Safari (iOS) | Firefox (Windows) | Node.js |
+|--------------|--------|---------|--------|------|---|----|------|-----|
+| WebAssembly (CPU)  |   ✔️    |    ✔️    |   ✔️   |  ✔️  |  ✔️  |  ✔️  |  ✔️  |  ✔️<sup>\[1]</sup>  |
+| WebGPU         |   ✔️<sup>\[2]</sup>    |    ✔️<sup>\[3]</sup>    |   ✔️   |  ❌  |  ❌  |  ❌  |  ❌  |  ❌  |
+| WebGL          |   ✔️<sup>\[4]</sup>    |    ✔️<sup>\[4]</sup>    |   ✔️<sup>\[4]</sup>   |  ✔️<sup>\[4]</sup>  |  ✔️<sup>\[4]</sup>  | ✔️<sup>\[4]</sup>  | ✔️<sup>\[4]</sup>  |  ❌  |
+| WebNN          |   ✔️<sup>\[5]</sup>    |    ❌    |   ❌   |  ❌  |  ❌  |  ❌  |  ❌  |  ❌  |
+
+- \[1]: Node.js only support single-threaded `wasm` EP.
+- \[2]: WebGPU requires Chromium v113 or later on Windows. Float16 support requires Chrome v121 or later, and Edge v122 or later.
+- \[3]: WebGPU requires Chromium v121 or later on Windows.
+- \[4]: WebGL support is in maintenance mode. It is recommended to use WebGPU for better performance.
+- \[5]: Requires to launch browser with commandline flag `--enable-experimental-web-platform-features`.