📕 Parse.CoreManager Request Headers #861

Hi ! 👋

It was a bit difficult to find that it was possible to add custom headers in each Parse client request. I did not find anything in the actual documentation or maybe I missed something.

Would it be possible to add documentation about this ? I would be happy to help

References:
parse-community/Parse-SDK-JS#1014
parse-community/Parse-SDK-JS#1019

Proposed solution:
In any SDK doc I suppose with a Parse.CoreManager entry. I am only using Parse JS SDK

Thanks!