Start README.rst with a better title

Now that we are using gitea the contents of our README.rst are
more prominently displayed. Starting it with a "Team and repository
tags" title is a bit confusing. This change makes it start with the
name of the project instead.

Change-Id: Icfce3764aa9e1aabf5e78443cf7ce102de63a052

README.rst

@@ -1,6 +1,6 @@
-========================
-Team and repository tags
-========================
+=======
+Watcher
+=======
 
 .. image:: https://governance.openstack.org/tc/badges/watcher.svg
     :target: https://governance.openstack.org/tc/reference/tags/index.html
@@ -13,10 +13,6 @@ Team and repository tags
 
           https://creativecommons.org/licenses/by/3.0/
 
-=======
-Watcher
-=======
-
 OpenStack Watcher provides a flexible and scalable resource optimization
 service for multi-tenant OpenStack-based clouds.
 Watcher provides a robust framework to realize a wide range of cloud