Fix a typo in Debugging docs
Fix a typo in Debugging docs

Summary: Remote debugging port for Flipper is 9222

Reviewed By: passy

Differential Revision: D19598819

fbshipit-source-id: a749615027fbd0ab998e09f96803055305e4f9d1

facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper