Docs: enhance FirebaseMessaging token sources comments (#13805)

FirebaseMessaging/Sources/Token/FIRMessagingTokenManager.m

@@ -744,15 +744,15 @@ - (void)setAPNSToken:(NSData *)APNSToken withUserInfo:(NSDictionary *)userInfo {
                                         handler:^(NSString *_Nullable token,
                                                   NSError *_Nullable error){
                                             // Do nothing as callback is not needed and the
-                                            // sub-funciton already handle errors.
+                                            // sub-function already handle errors.
                                         }];
       }
       if ([self->_tokenStore cachedTokenInfos].count == 0) {
         [self tokenWithAuthorizedEntity:self.fcmSenderID
                                   scope:kFIRMessagingDefaultTokenScope
                                 options:tokenOptions
                                 handler:^(NSString *_Nullable FCMToken, NSError *_Nullable error){
-                                    // Do nothing as callback is not needed and the sub-funciton
+                                    // Do nothing as callback is not needed and the sub-function
                                     // already handle errors.
                                 }];
       }