Fix verifying typo (#10792)

Author: paulb777

FirebaseAuth/Sources/Auth/FIRAuth.m

@@ -150,7 +150,7 @@
 static NSString *const kEmailLinkSignInRequestType = @"EMAIL_SIGNIN";
 
 /** @var kVerifyAndChangeEmailRequestType
-    @brief The action code type value for verifing and changing email in the check action code
+    @brief The action code type value for verifying and changing email in the check action code
            response.
  */
 static NSString *const kVerifyAndChangeEmailRequestType = @"VERIFY_AND_CHANGE_EMAIL";

FirebaseAuth/Sources/Public/FirebaseAuth/FIRAuth.h

@@ -194,7 +194,7 @@ typedef NS_ENUM(NSInteger, FIRActionCodeOperation) {
   /** Action code for email link operation. */
   FIRActionCodeOperationEmailLink = 4,
 
-  /** Action code for verifing and changing email */
+  /** Action code for verifying and changing email */
   FIRActionCodeOperationVerifyAndChangeEmail = 5,
 
   /** Action code for reverting second factor addition */