Adopting the common role documentation pattern

This bring the role in conformance with the documentation
pattern originated from the os_keystone role. This was
chosen as the standard pattern during the Newton design
summit.

Change-Id: Id1d965cc689fc42b1cdb0ff3cb46704f49b6d4b6

README.rst

@@ -1,15 +1,59 @@
-os_gnocchi role
-############
-:tags: openstack, cloud, ansible, os_gnocchi
-:category: \*nix
+OpenStack-Ansible Gnocchi
+#########################
 
-os_gnocchi Role
+Ansible role which installs and configures OpenStack Gnocchi. Gnocchi installs
+behind an Apache webserver listening for HTTP connections on port 8041 and
+writes to filesystem storage by default.
+
+The role can readily be configured to use Swift or Ceph storage as desired and
+may be used as a stand-alone service integrated with Keystone for auth or with
+Ceilometer as a metrics source.
+
+Default Variables
+=================
+
+.. literalinclude:: ../../defaults/main.yml
+   :language: yaml
+   :start-after: under the License.
+
+Required Variables
+==================
+
+This list is not considered exhaustive at present. See role internals for
+further details.
 
 .. code-block:: yaml
 
-    - name: os_gnocchi role
-      hosts: "hosts"
+    gnocchi_galera_password: "secrete"
+    galera_address: 10.100.100.2
+
+    # Keystone credentials
+    keystone_admin_tenant_name: admin
+    keystone_admin_user_name: admin
+    keystone_auth_admin_password: "SuperSecretePassword"
+    keystone_service_adminuri_insecure: false
+    keystone_service_adminurl: "https://10.100.100.10:35357/v3"
+    keystone_service_internalurl: "https://10.100.100.10:5000/v3"
+
+    # Keystone password for the gnocchi service user
+    gnocchi_service_password: "secrete"
+
+    # hostname or IP of load balancer providing external network
+    # access to Keystone
+    external_lb_vip_address: 10.100.100.102
+
+    # hostname or IP of load balancer providing internal network
+    # access to Keystone
+    internal_lb_vip_address: 10.100.100.102
+
+Example Playbook
+================
+
+..  code-block:: yaml
+
+    - name: Installation and setup of Keystone
+      hosts: keystone_all
       user: root
       roles:
-        - { role: "os_gnocchi" }
-
+        - { role: "os_keystone", tags: [ "os-keystone" ] }
+      vars: