Updated 'whats_new.rst' with a little bit more explanation of why you might use the 'image.composite_image' option.

breedlun · breedlun · commit 8b6d7c3a22db · 2015-03-02T20:00:20.000-07:00
diff --git a/doc/users/whats_new.rst b/doc/users/whats_new.rst
@@ -81,7 +81,9 @@ Configuration (rcParams)
 ``image.composite_image`` added
 ```````````````````````````````
 Controls whether vector graphics backends (i.e. PDF, PS, and SVG) combine
-multiple images on a set of axes into a single composite image.
+multiple images on a set of axes into a single composite image.  Saving each
+image individually can be useful if you wish to edit a matplotlib generated 
+vector graphics file in Inkscape or other programs.
 
 .. _whats-new-1-4:
 
