Remove old and invalid help

We don't need this anymore

client/src/app/+admin/system/debug/debug.component.html

@@ -13,7 +13,5 @@
   <p i18n>To fix it:<p>
   <ul>
     <li i18n>Check the <code>trust_proxy</code> configuration key</li>
-    <li i18n>If you run PeerTube using Docker, check you run the <code>reverse-proxy</code> with <code>network_mode: "host"</code>
-      (see <a href="https://github.com/Chocobozzz/PeerTube/issues/1643#issuecomment-464789666">issue 1643</a>)</li>
   </ul>
 </div>