ENGCOM-5859: Added description BraintreeInput #909

 - Merge Pull Request magento/graphql-ce#909 from sedonik/graphql-ce:description-braintreeinput
 - Merged commits:
   1. 3a56634
   2. 9bb976c
   3. d3cbe27
   4. 2ff66af

app/code/Magento/BraintreeGraphQl/etc/schema.graphqls

@@ -11,9 +11,9 @@ input PaymentMethodInput {
 }
 
 input BraintreeInput {
-    payment_method_nonce: String!
-    is_active_payment_token_enabler: Boolean!
-    device_data: String
+    payment_method_nonce: String! @doc(description:"The one-time payment token generated by Braintree payment gateway based on card details. Required field to make sale transaction.")
+    is_active_payment_token_enabler: Boolean! @doc(description:"States whether an entered by a customer credit/debit card should be tokenized for later usage. Required only if Vault is enabled for Braintree payment integration.")
+    device_data: String @doc(description:"Contains a fingerprint provided by Braintree JS SDK and should be sent with sale transaction details to the Braintree payment gateway. Should be specified only in a case if Kount (advanced fraud protection) is enabled for Braintree payment integration.")
 }
 
 input BraintreeCcVaultInput {