Improve developer's experience with docs

[abitrolly]

1. Promote virtualenvwrapper
2. Link to page source on GitHub from footer
3. Update year

This changes footer rendering.

Compared to the current version.

[codecov-io]

Codecov Report

Merging #693 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #693   +/-   ##
=======================================
  Coverage   95.71%   95.71%           
=======================================
  Files          57       57           
  Lines        2891     2891           
  Branches      395      395           
=======================================
  Hits         2767     2767           
  Misses         86       86           
  Partials       38       38

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