Add custom rosdoc2 config

[christophfroehlich]

rosdoc2 will be used by the build farm to publish API docs on http://docs.ros.org/en/rolling/p/realtime_tools/

• Add custom landing page for rosdoc2: logo, links to control.ros.org
• Copy over information from https://wiki.ros.org/realtime_tools
• add rosdoc2 workflow, but only if the relevant files changed

[fmauch]

+1 for per-package documentation :-)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.89%. Comparing base (99b6153) to head (42eb589).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #161   +/-   ##
=======================================
  Coverage   76.89%   76.89%           
=======================================
  Files           7        7           
  Lines         238      238           
  Branches      100      100           
=======================================
  Hits          183      183           
  Misses         27       27           
  Partials       28       28           

Flag	Coverage Δ
unittests	76.89% <ø> (ø)

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[saikishor]

LGTM