MANIFEST.in: add entire docs folder (not just rst)

When a release gets created the docs folder is missing the sphinx Makefile, config, static, and template folders which means it's not possible to build the docs with sphinx. This patch adds the missing pieces.

Author: jtriley

MANIFEST.in

@@ -4,5 +4,5 @@ include INSTALL
 include LICENSE
 include MANIFEST.in
 include README.md
-recursive-include docs *.rst
+recursive-include docs *
 prune docs/_build