[DOC] Add support page

[tsalo]

Closes #31.

Changes proposed in this pull request:

• Add page to docs for support and communication.
  • Points to GitHub for bug reports and feature requests, and NeuroStars for usage questions.
• Replace m2r with recommonmark for converting markdown to restructuredtext. This is related to a bug in m2r for Sphinx 3.0.0.
• Reorganize levels of headings in INSTALL.rst and README.rst, to clean up the RTD sidebar.
  • There are a number of cases of trailing whitespace that were automatically cleaned up by VSCode.

[codecov[bot]]

Codecov Report

Merging #33 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #33   +/-   ##
=======================================
  Coverage   27.47%   27.47%           
=======================================
  Files          54       54           
  Lines       14372    14372           
=======================================
  Hits         3948     3948           
  Misses      10424    10424           

---

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 c285894...920ff04. Read the comment docs.