Add formatting check for .md and .yaml files.

[codecov[bot]]

Codecov Report

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

Comparison is base (807ce39) 91.42% compared to head (f51bc0d) 91.42%. Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #151 +/- ## ======================================= Coverage 91.42% 91.42% ======================================= Files 25 25 Lines 816 816 ======================================= Hits 746 746 Misses 70 70 ```

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