[Documentation] MasterKey in Parse.File.destroy()

[dplewis]

The Parse.File.destroy() method in the JS SDK requires the use of masterKey according to documentation, to destroy a file. See JS SDK guide.

Setting masterKey: false or not setting it at all has no effect and deleting the file succeeds. You can only delete files server side.

I think we need to either change the docs or the code, they are currently inconsistent.

If we change the code we can add more options like sessionToken in the future.