Add note about podspec fix to changelog
Add note about podspec fix to changelog

Note that `GCC_TREAT_WARNINGS_AS_ERRORS` and `GCC_WARN_ABOUT_MISSING_NEWLINE` are removed from podspec.
braintree/braintree_ios,Feverup/braintree_ios,billCTG/braintree_ios,bytemarkinc/braintree_ios,EverettQuebral/braintree_ios,bytemarkinc/braintree_ios,Feverup/braintree_ios,billCTG/braintree_ios,Feverup/braintree_ios,TeachersPayTeachers/braintree_ios,bytemarkinc/braintree_ios,bytemarkinc/braintree_ios,TeachersPayTeachers/braintree_ios,braintree/braintree_ios,TeachersPayTeachers/braintree_ios,braintree/braintree_ios,bytemarkinc/braintree_ios,billCTG/braintree_ios,TeachersPayTeachers/braintree_ios,apascual/braintree_ios,apascual/braintree_ios,EverettQuebral/braintree_ios,apascual/braintree_ios,TeachersPayTeachers/braintree_ios,EverettQuebral/braintree_ios,EverettQuebral/braintree_ios,apascual/braintree_ios,Feverup/braintree_ios,billCTG/braintree_ios,EverettQuebral/braintree_ios,braintree/braintree_ios,billCTG/braintree_ios