Auto-document all resource types.

There are separate pages for OpenStack, AWS and Rackspace resources.

Currently the following sources are used for resource type documentation:
- the docstring for the resource class
- properties_schema
- attributes_schema

Change-Id: I901d227e8bc2a7209f216b57653da77a4f500e47

doc/source/template_guide/cfn.rst

@@ -0,0 +1,16 @@
+..
+      Licensed under the Apache License, Version 2.0 (the "License"); you may
+      not use this file except in compliance with the License. You may obtain
+      a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+      WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+      License for the specific language governing permissions and limitations
+      under the License.
+
+CloudFormation Compatible Resource Types
+----------------------------------------
+.. resourcepages:: AWS::

doc/source/template_guide/index.rst

@@ -17,4 +17,7 @@ Template Guide
 .. toctree::
    :maxdepth: 2
 
-   functions
+   functions
+   openstack
+   cfn
+   rackspace

doc/source/template_guide/openstack.rst

@@ -0,0 +1,17 @@
+..
+      Licensed under the Apache License, Version 2.0 (the "License"); you may
+      not use this file except in compliance with the License. You may obtain
+      a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+      WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+      License for the specific language governing permissions and limitations
+      under the License.
+
+
+OpenStack Resource Types
+------------------------
+.. resourcepages:: OS::

doc/source/template_guide/rackspace.rst

@@ -0,0 +1,16 @@
+..
+      Licensed under the Apache License, Version 2.0 (the "License"); you may
+      not use this file except in compliance with the License. You may obtain
+      a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+      WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+      License for the specific language governing permissions and limitations
+      under the License.
+
+Rackspace Cloud Resource Types
+------------------------------
+.. resourcepages:: Rackspace::