MANIFEST.in: add some missing files

MANIFEST.in

@@ -2,7 +2,9 @@ include versioneer.py
 include src/wormhole/_version.py
 include LICENSE README.md NEWS.md
 recursive-include docs *.md *.rst *.dot
-include docs/wormhole.1
+include docs/wormhole.1 docs/Makefile docs/conf.py
+include docs/state-machines/Makefile
 include .coveragerc tox.ini snapcraft.yaml
 include misc/windows-build.cmd
 include misc/*.py misc/web/*.html misc/web/*.js misc/web/*.css
+include pyi/*