Documented how to opt out from flipper on iOS
Documented how to opt out from flipper on iOS

Summary: More docs. Addresses https://github.com/facebook/flipper/issues/1326, https://github.com/facebook/flipper/issues/1215 and probably more

Reviewed By: jknoxville

Differential Revision: D26778514

fbshipit-source-id: dcadbad8f53f483d14e7fc54199756a697095309

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