Update README.md (#883)

The service definition "com.parse.fcm.ParseFirebaseMessagingService" was missing the ">" character at the end, causing error in AndroidManifest.xmll

fcm/README.md

@@ -29,7 +29,7 @@ Additional, you will register:
 
 ```xml
 <service
-    android:name="com.parse.fcm.ParseFirebaseMessagingService"
+    android:name="com.parse.fcm.ParseFirebaseMessagingService">
     <intent-filter>
         <action android:name="com.google.firebase.MESSAGING_EVENT"/>
     </intent-filter>
@@ -67,4 +67,4 @@ If you need to store the FCM token elsewhere outside of Parse, you can create yo
 
     This source code is licensed under the BSD-style license found in the
     LICENSE file in the root directory of this source tree. An additional grant
-    of patent rights can be found in the PATENTS file in the same directory.
+    of patent rights can be found in the PATENTS file in the same directory.