Setup new structure for v2 docs (#732)

## Which problem is this PR solving?
- Prepare for #731

## Description of the changes
- Add next-release-v2 directory for developing v2 documentation
- Do not include CLI flags into v2 during build

## How was this change tested?
- `make develop`

Signed-off-by: Yuri Shkuro <[email protected]>

Makefile

@@ -3,7 +3,7 @@ HUGO_THEME   = jaeger-docs
 THEME_DIR    := themes/$(HUGO_THEME)
 
 client-libs-docs:
-	@for d in $(shell ls -d content/docs/*); do \
+	@for d in $(shell ls -d content/docs/* | grep -v next-release-v2); do \
 		cp content/_client_libs/client-libraries.md $$d/; \
 		cp content/_client_libs/client-features.md $$d/; \
 		echo "copied content/_client_libs/*.md -> $$d/"; \

content/docs/next-release-v2/_index.md

@@ -0,0 +1,78 @@
+---
+title: Introduction
+weight: 1
+children:
+- title: Features
+  url: features
+---
+
+Welcome to Jaeger v2 documentation portal! Below, you'll find information for beginners and experienced Jaeger users.
+
+If you cannot find what you are looking for, or have an issue not covered here, we'd love to [hear from you](/get-in-touch).
+
+If you are new to distributed tracing, please take a look at the [Related Links](#related-links) section below.
+
+## About
+
+Jaeger is a distributed tracing platform released as open source by [Uber Technologies][ubeross].
+With Jaeger you can:
+
+* Monitor and troubleshoot distributed workflows
+* Identify performance bottlenecks
+* Track down root causes
+* Analyze service dependencies
+
+Uber published a blog post, [Evolving Distributed Tracing at Uber](https://eng.uber.com/distributed-tracing/), where they explain the history and reasons for the architectural choices made in Jaeger. [Yuri Shkuro](https://shkuro.com), creator of Jaeger, also published a book [Mastering Distributed Tracing](https://shkuro.com/books/2019-mastering-distributed-tracing/) that covers in-depth many aspects of Jaeger design and operation, as well as distributed tracing in general.
+
+## Features
+
+  * [OpenTracing](https://opentracing.io/)-inspired data model
+  * [OpenTelemetry](https://opentelemetry.io/) compatible
+  * Multiple built-in storage backends: Cassandra, Elasticsearch and in-memory
+  * Community supported external storage backends via the gRPC plugin: [ClickHouse](https://github.com/jaegertracing/jaeger-clickhouse)
+  * System topology graphs
+  * Adaptive sampling
+  * Service Performance Monitoring (SPM)
+  * Post-collection data processing
+
+See [Features](./features/) page for more details.
+
+## Technical Specs
+
+  * Backend components implemented in Go
+  * React/Javascript UI
+  * Supported storage backends:
+    * [Cassandra 3.4+](./deployment/#cassandra)
+    * [Elasticsearch 7.x, 8.x](./deployment/#elasticsearch)
+    * [Badger](./deployment/#badger---local-storage)
+    * [Kafka](./deployment/#kafka) - as an intermediate buffer
+    * memory storage
+    * Custom backends via [Remote Storage API](./deployment/#remote-storage)
+
+## Quick Start
+
+See [Getting Started](./getting-started).
+
+## Screenshots
+
+### Traces View
+[![Traces View](/img/traces-ss.png)](/img/traces-ss.png)
+
+### Trace Detail View
+[![Detail View](/img/trace-detail-ss.png)](/img/trace-detail-ss.png)
+
+### Service Performance Monitoring View
+![Service Performance Monitoring](/img/frontend-ui/spm.png)
+
+## Related links
+- [Take Jaeger for a HotROD ride](https://medium.com/jaegertracing/take-jaeger-for-a-hotrod-ride-233cf43e46c2) (blog)
+- [Evolving Distributed tracing At Uber Engineering](https://eng.uber.com/distributed-tracing/) (blog)
+- [Mastering Distributed Tracing](https://shkuro.com/books/2019-mastering-distributed-tracing/) (book)
+- [OpenTracing Tutorial (Java, Go, Python, Node.js, C#)](https://github.com/yurishkuro/opentracing-tutorial/) (tutorials)
+- [Learning Distributed Tracing 101](https://tracing.cloudnative101.dev/docs/index.html) (tutorials)
+- [Tracing HTTP request latency in Go with OpenTracing](https://medium.com/opentracing/tracing-http-request-latency-in-go-with-opentracing-7cc1282a100a) (blog)
+- [Distributed Tracing with Jaeger & Prometheus on Kubernetes](https://blog.openshift.com/openshift-commons-briefing-82-distributed-tracing-with-jaeger-prometheus-on-kubernetes/) (blog)
+- [Using Jaeger with Istio](https://istio.io/latest/docs/tasks/observability/distributed-tracing/jaeger/) (docs)
+- [Using Jaeger with Envoy](https://www.envoyproxy.io/docs/envoy/latest/start/sandboxes/jaeger_tracing.html) (docs)
+
+[ubeross]: http://uber.github.io