Fix HTML tag issue

Author: luchua-bc

java/ql/src/experimental/CWE-939/IncorrectURLVerification.qhelp

@@ -23,5 +23,6 @@ verification is implemented as partial domain match. In the 'GOOD' case, full do
 </li>
 <li>
 <a href="https://www.bugcrowd.com/resources/webinars/overview-of-common-android-app-vulnerabilities/">Common Android app vulnerabilities from bugcrowd</a>
+</li>
 </references>
 </qhelp>