added some more rules for dark remarkup environments
Summary:
Added rules for <tt> (` [inline code]) (did bright text on somewhat dark bg), NOTE: block and tables. These were all the ones I could think of and found that they required triage.
I did not touch minor things like links etc., which may require refinement. I try to stay away from design details.
Test Plan: {F35940}
Reviewers: chad, epriestley
Reviewed By: epriestley
CC: aran, Korvin
Differential Revision: https://secure.phabricator.com/D5345