Clarify comment above `tryToRemoveBlockStyle`
Clarify comment above `tryToRemoveBlockStyle`

Summary:
I found the comment above `RichUtils.tryToRemoveBlockStyle` a bit confusing while trying to understand the function's logic.

I would argue that the current comment's inclusion of information about where it is used is unnecessary, and makes it seem as if its interaction with those key commands was implemented inside the function itself.
Closes https://github.com/facebook/draft-js/pull/1135

Differential Revision: D5477479

fbshipit-source-id: a8cee503bf5459c63ac58504f5c112a1a249b64a

facebook/draft-js