Fix formatting of modification section

[odow]

Closes #401.

It seems I forgot to check the docs for errors in #388. The links weren't correct either.

This PR builds the docs without warnings and it looks like:

[codecov-io]

Codecov Report

Merging #402 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #402   +/-   ##
=======================================
  Coverage   95.51%   95.51%           
=======================================
  Files          40       40           
  Lines        5111     5111           
=======================================
  Hits         4882     4882           
  Misses        229      229

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