update readme
update readme

commercefactory/xx-braintree-dropin-cordova-angular-node,braintreedev/sample-braintree-dropin-cordova-angular-node,braintreedev/sample-braintree-dropin-cordova-angular-node,braintreedev/sample-braintree-dropin-cordova-angular-node,commercefactory/xx-braintree-dropin-cordova-angular-node,commercefactory/xx-braintree-dropin-cordova-angular-node,commercefactory/xx-braintree-dropin-cordova-angular-node,commercefactory/xx-braintree-dropin-cordova-angular-node,braintreedev/sample-braintree-dropin-cordova-angular-node,braintreedev/sample-braintree-dropin-cordova-angular-node