python: add MANIFEST.in

When creating a source or binary distribution via 'python3 setup.py
<sdist|bdist>', the VERSION and PACKAGE.rst files aren't bundled by
default. Create a MANIFEST.in file that instructs the build tools to
include these so that installation from these files won't fail.

This is required by 'tox', as well as by the tooling needed to upload
packages to PyPI.

Exclude the 'README.rst' file -- that's intended as a guidebook to our
source tree, not a file that needs to be distributed.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-id: 20210527211715.394144-14-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

python/MANIFEST.in

@@ -0,0 +1,3 @@
+include VERSION
+include PACKAGE.rst
+exclude README.rst

python/README.rst

@@ -33,6 +33,8 @@ Files in this directory
 -----------------------
 
 - ``qemu/`` Python package source directory.
+- ``MANIFEST.in`` is read by python setuptools, it specifies additional files
+  that should be included by a source distribution.
 - ``PACKAGE.rst`` is used as the README file that is visible on PyPI.org.
 - ``README.rst`` you are here!
 - ``VERSION`` contains the PEP-440 compliant version used to describe