docs: update AUTHORS.md [skip ci]

AUTHORS.md

@@ -356,6 +356,7 @@ authors.
       <td align="center" valign="top" width="12.5%"><a href="http://0atman.com"><img src="https://avatars.githubusercontent.com/u/114097?v=4?s=100" width="100px;" alt="Tristram Oaten"/><br /><sub><b>Tristram Oaten</b></sub></a><br /><a href="#content-0atman" title="Content">🖋</a></td>
       <td align="center" valign="top" width="12.5%"><a href="https://github.com/danieltinazzi"><img src="https://avatars.githubusercontent.com/u/11833533?v=4?s=100" width="100px;" alt="Daniel Tinazzi"/><br /><sub><b>Daniel Tinazzi</b></sub></a><br /><a href="#content-danieltinazzi" title="Content">🖋</a></td>
       <td align="center" valign="top" width="12.5%"><a href="https://github.com/raymon-roos"><img src="https://avatars.githubusercontent.com/u/38888470?v=4?s=100" width="100px;" alt="Raymon Roos"/><br /><sub><b>Raymon Roos</b></sub></a><br /><a href="#content-raymon-roos" title="Content">🖋</a></td>
+      <td align="center" valign="top" width="12.5%"><a href="https://github.com/matthri"><img src="https://avatars.githubusercontent.com/u/67913999?v=4?s=100" width="100px;" alt="Matthias"/><br /><sub><b>Matthias</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=matthri" title="Code">💻</a></td>
     </tr>
   </tbody>
 </table>