Update README with third-party exception ATS key
Update README with third-party exception ATS key

braintree/braintree_ios,billCTG/braintree_ios,apascual/braintree_ios,billCTG/braintree_ios,billCTG/braintree_ios,Feverup/braintree_ios,braintree/braintree_ios,Feverup/braintree_ios,braintree/braintree_ios,apascual/braintree_ios,apascual/braintree_ios,billCTG/braintree_ios,braintree/braintree_ios,billCTG/braintree_ios,Feverup/braintree_ios,Feverup/braintree_ios,apascual/braintree_ios