docs: update AUTHORS.md [skip ci]

AUTHORS.md

@@ -347,6 +347,7 @@ authors.
       <td align="center" valign="top" width="12.5%"><a href="https://github.com/offbyone"><img src="https://avatars.githubusercontent.com/u/181693?v=4?s=100" width="100px;" alt="Chris Rose"/><br /><sub><b>Chris Rose</b></sub></a><br /><a href="#infra-offbyone" title="Infrastructure (Hosting, Build-Tools, etc)">🚇</a></td>
       <td align="center" valign="top" width="12.5%"><a href="https://github.com/dieterplex"><img src="https://avatars.githubusercontent.com/u/507502?v=4?s=100" width="100px;" alt="d1t2"/><br /><sub><b>d1t2</b></sub></a><br /><a href="#infra-dieterplex" title="Infrastructure (Hosting, Build-Tools, etc)">🚇</a></td>
       <td align="center" valign="top" width="12.5%"><a href="https://github.com/docwilco"><img src="https://avatars.githubusercontent.com/u/66911096?v=4?s=100" width="100px;" alt="docwilco"/><br /><sub><b>docwilco</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=docwilco" title="Code">💻</a></td>
+      <td align="center" valign="top" width="12.5%"><a href="https://www.linkedin.com/in/matthew-nield1/"><img src="https://avatars.githubusercontent.com/u/64328730?v=4?s=100" width="100px;" alt="Matt Nield"/><br /><sub><b>Matt Nield</b></sub></a><br /><a href="#content-matthewjnield" title="Content">🖋</a></td>
     </tr>
   </tbody>
 </table>