readme: add link to mdview MTX project

[step-]

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 91.74%. Comparing base (481fbfb) to head (0eded20).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #267   +/-   ##
=======================================
  Coverage   91.74%   91.74%           
=======================================
  Files           5        5           
  Lines        3366     3366           
  Branches      766      766           
=======================================
  Hits         3088     3088           
  Misses        278      278           

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.