Separate module reference from contributor/index page

Change-Id: I9acbbb32d83d194f8d827101a0604b45d61f96f7

doc/source/contributor/index.rst

@@ -30,7 +30,10 @@ Developer reference
    database_migrations
    domain_model
    domain_implementation
-   api/autoindex
+.. toctree::
+   :maxdepth: 1
+
+   modules
 
 Policies
 --------

doc/source/contributor/modules.rst

@@ -0,0 +1,20 @@
+..
+      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.
+
+Module Reference
+================
+
+.. toctree::
+   :maxdepth: 1
+
+   api/autoindex