Add docs/conf.py and docs/Makefile to manifest. Closes #473

MANIFEST.in

@@ -9,5 +9,6 @@ include supervisor/version.txt
 include supervisor/skel/*.conf
 include supervisor/tests/fixtures/*.conf
 recursive-include supervisor/ui *.html *.css *.png *.gif
-recursive-include docs *.rst *.css *.gif *.png
+include docs/Makefile
+recursive-include docs *.py *.rst *.css *.gif *.png
 recursive-exclude docs/.build *