Manual page config

[frenzymadness]

Hello.

Would it be possible to fix sphinx configuration for manual pages? The current build of manual pages produces this warning and ends up with an empty folder:

# make man
sphinx-build -b man -d _build/doctrees   . _build/man
Running Sphinx v3.5.1
making output directory... done
loading pickled environment... done
building [mo]: targets for 0 po files that are out of date
building [man]: all manpages
updating environment: 0 added, 0 changed, 0 removed
looking for now-outdated files... none found
writing... WARNING: "man_pages" config value references unknown document index_
done
build succeeded, 1 warning.

The manual pages are in _build/man.

Build finished. The manual pages are in _build/man.

# ls -a _build/man
.  ..

[akx]

(related Fedora bug: https://bugzilla.redhat.com/show_bug.cgi?id=1611174)