[doc] Improve javadoc

Author: adamretter

exist-core/src/main/java/org/exist/storage/NotificationService.java

@@ -77,8 +77,8 @@ public synchronized void unsubscribe(final UpdateListener listener) {
      * Notify all subscribers that a document has been updated/removed or
      * a new document has been added.
      *
-     * @param document subscribers are listining to
-     * @param event that triggers the notify
+     * @param document subscribers are listening to
+     * @param event the event that triggers the notification
      */
     public synchronized void notifyUpdate(final DocumentImpl document, final int event) {
         listeners.keySet().forEach(listener -> listener.documentUpdated(document, event));

exist-core/src/main/java/org/exist/xquery/XQueryContext.java

@@ -3443,7 +3443,7 @@ private static class ContextUpdateListener implements UpdateListener {
          *
          * The AtomicReference enables us to quickly clear the listeners
          * in #unsubscribe() and maintain happens-before integrity whilst
-         * unsubcribing them. The CopyOnWriteArrayList allows
+         * unsubscribing them. The CopyOnWriteArrayList allows
          * us to add listeners whilst iterating over a snapshot
          * of existing iterators in other methods.
          */