Add link to codeberg

Well, maybe a future me may find such a link helpful
(maybe I would have forgotten about my account at Codeberg,
in the future? Who knows?)

dvcs.html

@@ -20,16 +20,20 @@
     
   </ol>
   </p>
-<p>Online, my Git-related accounts are the following:
+<p>As of 21st June 2020, my online Git-related accounts are the following:
   <ul>
     <li><a href="https://github.com/phtan/">
-      Github, at the user-name phtan
+      Github, at the user-name "phtan"
       </a>
     </li>
     <li><a href="https://gitlab.com/phtan">
       Gitlab, at the same user-name
       </a>
     </li>
+    <li><a href="https://codeberg.org/phtan">
+      Codeberg, at the same user-name
+      </a>
+    </li>
 </ul>
 </p>
 </div>