revert changes of providing return type for addSubscriptionSet() method on subscriptionSet entity

Author: Mohit Tejani

docs-snippets/publish-subscribe.ts

@@ -234,10 +234,10 @@ const subscriptionSet2 = pubnub.subscriptionSet({
   subscriptionOptions: { receivePresenceEvents: true } 
 });
 
-// create a new subscription set from 2 sets
-const subscriptionSet3 = subscriptionSet1.addSubscriptionSet(subscriptionSet2);
+// add a subscription set to another subscription set
+subscriptionSet1.addSubscriptionSet(subscriptionSet2);
 
-// you can also remove sets
-const subscriptionSetWithChannelsOnly = subscriptionSet3.removeSubscriptionSet(subscriptionSet2);
+// remove a subscription set from another subscription set
+subscriptionSet1.removeSubscriptionSet(subscriptionSet2);
 // snippet.end
 }

lib/types/index.d.ts

@@ -4767,7 +4767,7 @@ declare namespace PubNub {
      *
      * @param subscriptionSet - Other entities' subscription set, which should be joined.
      */
-    addSubscriptionSet(subscriptionSet: SubscriptionSet): SubscriptionSet;
+    addSubscriptionSet(subscriptionSet: SubscriptionSet): void;
     /**
      * Subtract another {@link SubscriptionSet} object.
      *