Link to config file instructions. References Supervisor#1433

Author: mnaberez

docs/configuration.rst

@@ -1532,8 +1532,8 @@ Adding ``rpcinterface:x`` settings in the configuration file is only
 useful for people who wish to extend supervisor with additional custom
 behavior.
 
-In the sample config file, there is a section which is named
-``[rpcinterface:supervisor]``.  By default it looks like the
+In the sample config file (see :ref:`create_config`), there is a section
+which is named ``[rpcinterface:supervisor]``.  By default it looks like the
 following.
 
 .. code-block:: ini

docs/installing.rst

@@ -101,6 +101,8 @@ the system boots.
     `Ubuntu Bug #1594740 <https://bugs.launchpad.net/ubuntu/+source/supervisor/+bug/1594740>`_
     for more information.
 
+.. _create_config:
+
 Creating a Configuration File
 -----------------------------