doc: move graphviz material to developer-guides

Rather than a "tutorial", it was suggested to move the graphviz
information to the devleoper-guides, along with the documentation
guidelines.  Makes sense.

Signed-off-by: David B. Kinder <david.b.kinder@intel.com>

doc/developer-guides/doc_guidelines.rst

@@ -393,3 +393,42 @@ the first non-white space in the preceding line.  For example:
 Keep the line length for documentation less than 80 characters to make
 it easier for reviewing in GitHub. Long lines because of URL references
 are an allowed exception.
+
+Drawings
+********
+
+You can include a picture (.jpg, .png, .svg for example) by using the
+``.. image`` directive::
+
+   .. image:: ../images/ACRNlogo.png
+      :align: center
+
+This results in the image being placed in the document:
+
+.. image:: ../images/ACRNlogo.png
+   :align: center
+
+Alternatively, use the ``.. figure`` directive to include a picture with
+a caption and automatic figure numbering for
+your image, (so you can say see :numref:`acrn-logo-figure`, by using the
+notation ``:numref:`acrn-logo-figure``` and specifying the name of
+figure)::
+
+   .. figure:: ../images/ACRNlogo.png
+      :align: center
+      :name: acrn-logo-figure
+
+      Caption for the figure
+
+.. figure:: ../images/ACRNlogo.png
+   :align: center
+   :name: acrn-logo-figure
+
+   Caption for the figure
+
+
+We've also included the ``graphviz`` Sphinx extension to let you use a text
+description language to render drawings.  See :ref:`graphviz-examples` for more
+information.
+
+

doc/developer-guides/graphviz.rst

@@ -1,4 +1,4 @@
-.. graphviz-examples:
+.. _graphviz-examples:
 
 Drawings using graphviz
 #######################

doc/developer-guides/index.rst

@@ -23,3 +23,4 @@ project.
 
    contribute_guidelines.rst
    doc_guidelines.rst
+   graphviz.rst