Update changelog

Author: ywarnier

documentation/changelog.html

@@ -192,6 +192,7 @@ <h4>For developers and sysadmins</h4>
         </ul>
         <h3>Improvements (minor features) and debug</h3>
         <ul aria-live="off">
+            <li>[2020-12-01] (<a href="https://github.com/chamilo/chamilo-lms/commit/f17e5c42f0bc6044a90289dc11fd20aa6d14e4ec">f17e5c42</a>) Exercise: Remove previous type definition in method arguments blocking in PHP 7.1</li>
             <li>[2020-11-30] (<a href="https://github.com/chamilo/chamilo-lms/commit/4676929a10cc6a2d4ed4bf6db38534ebac15e221">4676929a</a>) Install: Hard-set files and directories permissions to avoid deprecation warning with PHP 7.4 at install time</li>
             <li>[2020-11-30] (<a href="https://github.com/chamilo/chamilo-lms/commit/0a4b5f1a779bd16510a7213d37336d89e47022d8">0a4b5f1a</a>) Fix HookDocument and HookDocumentItem hooks</li>
             <li>[2020-11-30] (<a href="https://github.com/chamilo/chamilo-lms/commit/fb048378cf5dd73af3bac6ad03b578068f2d093f">fb048378</a> - <a href="https://task.beeznest.com/issues/16742">BT#16742</a>) XAPI: Fix namespace</li>