code documentation

[hexylena]

small goodbye present from me, since I'm the primary (only) ruby code maintainer.

• adds RDoc for lint.rb
• uses that RDoc + our deployed rdoc to replace the poorly maintained wiki we were using for the same (see GTN matrix channel message from Katherine), wiki is disabled.
• fixes longstanding issue with parsing markdown files for the 'bad header' issue. It is now replaced with kramdown to properly parse the file.
• adds some Architectural Decision Records for some of our architecture choices that have been brought up recently (jekyll, why images in git)
• improves video page (/videos/ and /videos/watch.html)
• moves author pages (Hall of fame) to development env
• moves API, by-tag to production only (they were before but they're again now.)

Updated Linting Docs

Linting comments will now point to the GTN RDoc with the explanations kept in sync with the code:

Helpful Jekyll Internal Documentation

Specific to us

Improved Overall Docs

[hexylena]

not necessarily ready for review, but ready for tests to execute.

[shiltemann]

thanks @hexylena !