docs: Formatted spacing and updated documentation (#3290)

* Refactored redundant spacing in pom.xml

* Updated documentation of remove subscriber in publish-subscribe model

publish-subscribe/src/main/java/com/iluwatar/publish/subscribe/model/Topic.java

@@ -51,7 +51,7 @@ public class Topic {
   }
 
   /**
-   * Remove a subscriber to the list of subscribers.
+   * Remove a subscriber from the list of subscribers.
    *
    * @param subscriber subscriber to remove
    */