action: implemented and added README

.github/workflows/setup_atlas.yml

@@ -0,0 +1,10 @@
+name: Setup Atlas
+run-name: I'm using Atlas 🚀
+on: [push]
+jobs:
+  use-atlas:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+      - run: atlas version

README.md

@@ -1,2 +1,43 @@
-# setup-atlas
-A GitHub Action to install ariga/atlas in your workflows.
+# setup-action
+
+A GitHub Action for installing [Atlas](https://github.com/ariga/atlas).
+
+> See the docs for other [Atlas GitHub Actions](https://atlasgo.io/integrations/github-actions) for operations such as linting, syncing, or deploying your migration directory. 
+
+## Usage
+
+Add `.github/workflows/deploy-schema.yaml` to your repo with the following contents:
+
+```yaml
+name: Deploy schema changes
+run-name: I'm using Atlas 🚀
+on: [push]
+jobs:
+  use-atlas:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: ariga/setup-atlas@master
+      - run: atlas version
+      # - run: atlas schema apply ... 
+```
+
+## Inputs
+
+### Version
+
+By default, the `latest` version of Atlas is being used. If you want to lock a specific version of Atlas, you can do so by specifing the `version` parameter.
+
+```yaml
+      - uses: ariga/setup-atlas@master
+        with:
+            version: "vX.Y.Z"
+```
+
+
+## Legal
+
+The source code for this GitHub Action is released under the Apache 2.0
+License, see [LICENSE](LICENSE).
+
+This action downloads a binary version of [Atlas](https://atlasgo.io) which
+is distributed under the [Ariga EULA](https://ariga.io/legal/atlas/eula).

action.yml

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+name: 'Installs Atlas'
+description: 'Installs a specific version of Atlas'
+branding:
+  icon: database
+author: 'Ariga'
+inputs:
+  version:
+    description: 'Which version of Atlas to install, in the format of "v0.14.1"'
+    required: false
+    default: 'latest'
+runs:
+  using: "composite"
+  steps:
+    - run: curl -sSf https://atlasgo.sh | ATLAS_VERSION=${{inputs.version}} CI=true sh
+      shell: bash
+