update dev docs and add recommonmark as a test dependency

[luizirber]

Checklist

• Is it mergeable?
• make test Did it pass the tests?
• make coverage Is the new code covered?
• Did it change the command-line interface? Only additions are allowed
  without a major version increment. Changing file formats also requires a
  major version number increment.
• Was a spellchecker run on the source code and documentation after
  changes were made?

[codecov]

Codecov Report

Merging #805 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #805   +/-   ##
=======================================
  Coverage   79.59%   79.59%           
=======================================
  Files          45       45           
  Lines        6588     6588           
  Branches      454      454           
=======================================
  Hits         5244     5244           
  Misses       1043     1043           
  Partials      301      301

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3febb3f...68b8a1d. Read the comment docs.

[luizirber]

ready for review and merge @ctb