Update 2-ui/99-ui-misc/01-mutation-observer/article.md

Co-authored-by: Muhammed Zakir <8190126+MuhammedZakir@users.noreply.github.com>

Author: peachesontour

2-ui/99-ui-misc/01-mutation-observer/article.md

@@ -252,7 +252,7 @@ let mutationRecords = observer.takeRecords();
 ```
 
 ```smart header="Garbage collection interaction"
-Observers use weak references to nodes internally. That is: if a node is removed from the DOM, and becomes unreachable, then it can be garbage collected.
+Observers use weak references to nodes internally. That is, if a node is removed from the DOM, and becomes unreachable, then it can be garbage collected.
 
 The mere fact that a DOM node is observed doesn't prevent the garbage collection.
 ```