Watcher official install-guide

Currently watcher project does not have an official
install guide at [1]

This patch adds watcher install guide for rdo and debian.

install-guide is written following the document [2].

[1] https://docs.openstack.org/project-install-guide/ocata/
[2] https://docs.openstack.org/contributor-guide/project-install-guide.html

Change-Id: Idfae7286003f81222dadf91ddcaf95a42c7eb07f

install-guide/source/get_started.rst

@@ -0,0 +1,27 @@
+============================================
+Infrastructure Optimization service overview
+============================================
+The Infrastructure Optimization service provides flexible and scalable
+optimization service for multi-tenant OpenStack based clouds.
+
+The Infrastructure Optimization service consists of the following components:
+
+``watcher`` command-line client
+  A CLI to communicate with ``watcher-api`` to optimize the cloud.
+
+``watcher-api`` service
+  An OpenStack-native REST API that accepts and responds to end-user calls
+  by processing them and forwarding to appropriate underlying watcher
+  services via AMQP.
+
+``watcher-decision-engine`` service
+  It runs audit and return an action plan to achieve optimization goal
+  specified by the end-user in audit.
+
+``watcher-applier`` service
+  It executes action plan built by watcher-decision-engine. It interacts with
+  other OpenStack components like nova to execute the given action
+  plan.
+
+``watcher-dashboard``
+  Watcher UI implemented as a plugin for the OpenStack Dashboard.