Illustrate index dependency rules

Add diagrams to show correct and incorrect index relationships in a Kubernetes/Openstack doc.

Change-Id: I219cfad24f54d6ee4c7d4cafef36bd131693f7db
Signed-off-by: Ron Stone <ronald.stone@windriver.com>

doc/source/contributor/doc_contribute_guide.rst

@@ -284,10 +284,22 @@ random strings ``768a6e9aaeff`` and ``1b466179efc3`` were added by
    Additional indexes, either at the root of the document or in subfolders, are
    not allowed.
 
+   The following images provide examples of correct and incorrect layouts.
+
+   .. figure:: figures/index-structure-ok-2.png
+
+      **Correct Kubernetes/OpenStack layout**
+
+
+   .. figure:: figures/index-structure-wrong.png
+
+      **Incorrect Kubernetes/OpenStack layout**
+
+
    Use section headings in the index file to define document structure. For
    example:
 
-.. code-block::
+   .. code-block::
 
       .. _contribute: