Update index.src.html

Fixing markup

Author: caribouW3

index.src.html

@@ -673,7 +673,7 @@ <h2 id="observers">Reporting Observers</h2>
   an observer could first be created, or before a JavaScript library is loaded
   that wishes to observe these reports.
 
-  Note: </a>Reporting observers</a> are only relevant for user agents with
+  Note: <a>Reporting observers</a> are only relevant for user agents with
   JavaScript engines.
 
   <h3 id=interface-reporting-observer>Interface {{ReportingObserver}}</h3>