Setuptools v54.1.0 introduces a warning that the use of dash-separated
options in 'setup.cfg' will not be supported in a future version [1].
Get ahead of the issue by replacing the dashes with underscores. Without
this, we see 'UserWarning' messages like the following on new enough
versions of setuptools:
UserWarning: Usage of dash-separated 'description-file' will not be
supported in future versions. Please use the underscore name
'description_file' instead
Change-Id: I35db22f4413dcc2809d1ef892bd08006fe757446
Make a few cleanups:
- Remove obsolete sections from setup.cfg
- Switch to using sphinx-build
- Cleanup doc/source/conf.py to remove now obsolete content.
- Use newer openstackdocstheme version
- Remove install_command from tox.ini, the default is fine;
cleanup for Python 3 only
- Fix sphinx warnings
Change-Id: Ic70971b3c927508cd8a69b74f0c6b152671e8f83
liyou01