improve the documentation for option location information

Fix an error in the example code by setting loc to the Location enum
value instead of the LocationInfo tuple.

Add a cross-reference from the ConfigOpts get_location() method to the
more extensive reference documentation about option locations.

Change-Id: Ic9850afd78a7b42f4e807b04e78729a674942e15
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

doc/source/reference/locations.rst

@@ -58,7 +58,7 @@ user-controlled separately.
 
 .. code-block:: python
 
-   loc = CONF.get_location('normal_opt')
+   loc = CONF.get_location('normal_opt').location
    if loc.is_user_controlled:
       print('normal_opt was set by the user')
    else:

oslo_config/cfg.py

@@ -3383,6 +3383,10 @@ class ConfigOpts(collections.Mapping):
         :type group: str
         :return: LocationInfo
 
+        .. seealso::
+
+           :doc:`/reference/locations`
+
         .. versionadded:: 5.3.0
         """
         value, loc = self._do_get(name, group, None)