add and scale TFG

docs/dev_guide/custom_field/tripal_field_generator.rst

@@ -1,4 +1,9 @@
-Easier Field Creation: Tripal Field Generator 
-============================================
+Easier Field Creation: Tripal Field Generator
+==============================================
 
-The Staton Lab has created a `specialized tool <https://github.com/statonlab/fields_generator>`_ for automatically generating a ChadoField or TripalField and populating them with the basic controlled vocabulary and database information.  Instructions are available at https://github.com/statonlab/fields_generator.
+
+The Staton Lab has created a `specialized tool <https://github.com/statonlab/fields_generator>`_ for automatically generating a ChadoField or TripalField and populating them with the basic controlled vocabulary and database information.  Instructions are available at https://github.com/statonlab/fields_generator.
+
+.. figure:: tripal_field_generator.TFG.png
+   :align: center
+   :scale: 50%