Post release fixups

See:

- https://github.com/Pylons/zodburi/pull/30#discussion_r631002984
- https://github.com/Pylons/zodburi/pull/30#discussion_r631011936
- https://github.com/Pylons/zodburi/pull/30#discussion_r631012742

MANIFEST.in

@@ -3,7 +3,7 @@ prune docs/_build
 graft zodburi
 
 include README.rst
-include RELEASING.txt
+exclude RELEASING.txt
 include CHANGES.rst
 include contributing.md
 include CONTRIBUTORS.txt

RELEASING.txt

@@ -16,7 +16,7 @@ See zest.releaser documentation for details:
 https://zestreleaser.readthedocs.io/en/latest/overview.html#available-commands
 
 
-If/when needed, one could also manually make all release steps described above.
+If needed, one could instead manually make all release steps described above.
 See "Packaging Python Projects"
 
 https://packaging.python.org/tutorials/packaging-projects/

tox.ini

@@ -40,7 +40,6 @@ deps =
     Sphinx
     pylons-sphinx-themes
 
-
 [testenv:lint]
 skip_install = true
 commands =