Clarified header docs for generated files.
Clarified header docs for generated files.

hibu/facebook-ios-sdk,flovilmart/facebook-ios-sdk,hibu/facebook-ios-sdk,1234-/facebook-ios-sdk,1234-/facebook-ios-sdk,shepting/facebook-ios-sdk,flovilmart/facebook-ios-sdk,flovilmart/facebook-ios-sdk,1234-/facebook-ios-sdk,flovilmart/facebook-ios-sdk,hibu/facebook-ios-sdk,shepting/facebook-ios-sdk,1234-/facebook-ios-sdk,flovilmart/facebook-ios-sdk,shepting/facebook-ios-sdk,hibu/facebook-ios-sdk,hibu/facebook-ios-sdk,shepting/facebook-ios-sdk,shepting/facebook-ios-sdk,1234-/facebook-ios-sdk