Update index.xml

Author: pstack2021

site/index.xml

@@ -267,7 +267,7 @@ limitations under the License.
                 <h2>Other inquiries</h2>
                 <p><a href="./contact.html">Contact us</a></p>
                 <h2>Report a security vulnerability</h2>
-                <p><a href="mailto:[email protected]</a></p>
+                <p><a href="mailto:[email protected]"</a></p>
                 <h2>Social media</h2>
                 <p><a href='https://twitter.com/RabbitMQ' target="_blank" rel="noopener noreferrer">Twitter</a></p>
               </div>