fix a few minor issues, finish up howto docs

Author: bckohan

doc/source/conf.py

@@ -43,7 +43,9 @@
     'sphinxcontrib_django',
     'sphinx.ext.intersphinx',
     'sphinx.ext.autodoc',
-    'sphinx.ext.todo'
+    'sphinx.ext.todo',
+    'sphinx_tabs.tabs',
+    "sphinx.ext.viewcode",
 ]
 
 # Add any paths that contain templates here, relative to this directory.

doc/source/howto/flags.rst

@@ -12,6 +12,8 @@ Python supports `bit fields <https://en.wikipedia.org/wiki/Bit_field>`_ through
 These enumerations are fully supported and will render as multi select form fields by default. For
 example:
 
+.. _group_permissions_ex:
+
 .. literalinclude:: ../../../tests/examples/models/flag_howto.py
     :lines: 2-