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/install.rst

@@ -0,0 +1,20 @@
+.. _install:
+
+Install and configure
+~~~~~~~~~~~~~~~~~~~~~
+
+This section describes how to install and configure the
+Infrastructure Optimization service, code-named watcher, on the controller node.
+
+This section assumes that you already have a working OpenStack
+environment with at least the following components installed:
+Identity Service, Compute Service, Telemetry data collection service.
+
+Note that installation and configuration vary by distribution.
+
+.. toctree::
+   :maxdepth: 2
+
+   install-obs.rst
+   install-rdo.rst
+   install-ubuntu.rst