make it more clear how to run mdoc (#4487)
make it more clear how to run mdoc (#4487)

* make it more clear how to run mdoc

* Update CONTRIBUTING.md

Co-authored-by: kellen <a718b3bf598cb3d5e7065ee4e6864892434c6021@users.noreply.github.com>

Co-authored-by: kellen <a718b3bf598cb3d5e7065ee4e6864892434c6021@users.noreply.github.com>
spotify/scio,spotify/scio,spotify/scio,spotify/scio