Remove TODO to add documentation link.

Author: tusharkhandelwal8

firebase-config/src/main/java/com/google/firebase/remoteconfig/FirebaseRemoteConfig.java

@@ -667,7 +667,6 @@ private Task<Void> setDefaultsWithStringsMapAsync(Map<String, String> defaultsSt
    *   <li>Setting a key's value to {@code null} will remove the associated signal.
    * </ul>
    */
-  // TODO(b/385028620): Add link to documentation about custom signal limits.
   @NonNull
   public Task<Void> setCustomSignals(@NonNull CustomSignals customSignals) {
     return Tasks.call(