docs: add manuelfs as a contributor for code (#454)

* docs: update README.md [skip ci]

* docs: update .all-contributorsrc [skip ci]

---------

Co-authored-by: allcontributors[bot] <46447321+allcontributors[bot]@users.noreply.github.com>

.all-contributorsrc

@@ -91,6 +91,15 @@
       "contributions": [
         "code"
       ]
+    },
+    {
+      "login": "manuelfs",
+      "name": "Manuel Franco Sevilla",
+      "avatar_url": "https://avatars.githubusercontent.com/u/4977423?v=4",
+      "profile": "https://github.com/manuelfs",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "contributorsPerLine": 7,

README.md

@@ -274,6 +274,7 @@ We hereby acknowledge the contributors that made this project possible ([emoji k
     <tr>
       <td align="center" valign="top" width="14.28%"><a href="https://gitlab.cern.ch/users/admorris"><img src="https://avatars.githubusercontent.com/u/15155249?v=4?s=100" width="100px;" alt="Adam Morris"/><br /><sub><b>Adam Morris</b></sub></a><br /><a href="https://github.com/scikit-hep/decaylanguage/commits?author=admorris" title="Code">💻</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/ch2ohch2oh"><img src="https://avatars.githubusercontent.com/u/7986711?v=4?s=100" width="100px;" alt="Dazhi Wang"/><br /><sub><b>Dazhi Wang</b></sub></a><br /><a href="https://github.com/scikit-hep/decaylanguage/commits?author=ch2ohch2oh" title="Code">💻</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="https://github.com/manuelfs"><img src="https://avatars.githubusercontent.com/u/4977423?v=4?s=100" width="100px;" alt="Manuel Franco Sevilla"/><br /><sub><b>Manuel Franco Sevilla</b></sub></a><br /><a href="https://github.com/scikit-hep/decaylanguage/commits?author=manuelfs" title="Code">💻</a></td>
     </tr>
   </tbody>
 </table>