Adapt watcher documentation for new standards

This patch set makes the following changes:

 * Add index file to each subdirectory of doc/source
 * Update doc/source/index.rst with new links
 * Move content of install-guide to the doc/source/install
 * Minor changes

Depends-On: Ifc5512c0e2373cf3387e0e0498268eab092e52bb
Change-Id: Iecb4f60efb015a56b9b37331859848b287112842

doc/source/contributor/plugin/plugins.rst

@@ -0,0 +1,76 @@
+..
+      Except where otherwise noted, this document is licensed under Creative
+      Commons Attribution 3.0 License.  You can view the license at:
+
+          https://creativecommons.org/licenses/by/3.0/
+
+
+=================
+Available Plugins
+=================
+
+In this section we present all the plugins that are shipped along with Watcher.
+If you want to know which plugins your Watcher services have access to, you can
+use the :ref:`Guru Meditation Reports <watcher_gmr>` to display them.
+
+.. _watcher_goals:
+
+Goals
+=====
+
+.. list-plugins:: watcher_goals
+   :detailed:
+
+.. _watcher_scoring_engines:
+
+Scoring Engines
+===============
+
+.. list-plugins:: watcher_scoring_engines
+   :detailed:
+
+.. _watcher_scoring_engine_containers:
+
+Scoring Engine Containers
+=========================
+
+.. list-plugins:: watcher_scoring_engine_containers
+   :detailed:
+
+.. _watcher_strategies:
+
+Strategies
+==========
+
+.. list-plugins:: watcher_strategies
+   :detailed:
+
+.. _watcher_actions:
+
+Actions
+=======
+
+.. list-plugins:: watcher_actions
+   :detailed:
+
+.. _watcher_workflow_engines:
+
+Workflow Engines
+================
+
+.. list-plugins:: watcher_workflow_engines
+   :detailed:
+
+.. _watcher_planners:
+
+Planners
+========
+
+.. list-plugins:: watcher_planners
+   :detailed:
+
+Cluster Data Model Collectors
+=============================
+
+.. list-plugins:: watcher_cluster_data_model_collectors
+   :detailed: