Fixed #22442 -- Provided additional documentation regarding id fields clashing.

Thanks benjaoming for raising the issue and Loic for the examples.

docs/releases/1.7.txt

@@ -1194,6 +1194,7 @@ Miscellaneous
   fields in the model inheritance hierarchy results in a system check error.
   For example, if you use multi-inheritance, you need to define custom primary
   key fields on parent models, otherwise the default ``id`` fields will clash.
+  See :ref:`model-multiple-inheritance-topic` for details.
 
 * ``django.utils.translation.parse_accept_lang_header()`` now returns
   lowercase locales, instead of the case as it was provided. As locales should