Refactor RCCL install guide into several pages (#1427)

* Refactor RCCL install guide into several pages

* Changes from code review and new docker guide

* Add missing entries to ToC

* Minor fixes

* Fix help strings

* Edits after review and remove extra white space

docs/sphinx/_toc.yml.in

@@ -9,10 +9,23 @@ subtrees:
   entries:
   - file: install/installation
     title: Installation guide
+  - file: install/docker-install
+    title: Running RCCL using Docker
+  - file: install/building-installing
+    title: Building and installing from source
 
 - caption: How to 
   entries:
   - file: how-to/using-nccl
+    title: Using the NCCL Net plugin
+  - file: how-to/rccl-usage-tips
+
+- caption: Examples
+  entries:
+  - url: https://github.com/ROCm/rccl/tree/develop/ext-tuner/example
+    title: RCCL Tuner plugin examples
+  - url: https://github.com/ROCm/rccl/tree/develop/ext-net/example
+    title: NCCL Net plugin examples
 
 - caption: API reference 
   entries: