Build docs locally

[stsewd]

Currently make html will output pages without styles
or different from the online documentation.

With this change the local documentation looks the same as the online
documentation.

[codecov-io]

Codecov Report

Merging #867 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@ Coverage Diff @@## master #867 +/- ##
==========================================
- Coverage 94.67% 94.66% -0.02% 
==========================================
Files 59 59 Lines 9393 9389 -4 ==========================================
- Hits 8893 8888 -5 - Misses 500 501 +1

Impacted Files	Coverage Δ
git/test/test_remote.py	97.54% <0%> (-0.28%)	⬇️
git/cmd.py	83.83% <0%> (-0.14%)	⬇️

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[Byron]

Thanks a lot! This PR is much appreciated!