Justify discouraging format on compile
Justify discouraging format on compile

Pushing the comments made in https://github.com/typelevel/cats/pull/2567#issuecomment-432229443 into the docs.

scalameta/scalafmt,olafurpg/scalafmt,scalameta/scalafmt,olafurpg/scalafmt,olafurpg/scalafmt,olafurpg/scalafmt,scalameta/scalafmt,scalameta/scalafmt