docs: add mboettcher as a contributor for code (#1063)

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

Author: allcontributors[bot]

.all-contributorsrc

@@ -1317,6 +1317,15 @@
         "bug",
         "code"
       ]
+    },
+    {
+      "login": "mboettcher",
+      "name": "Martin Böttcher",
+      "avatar_url": "https://avatars.githubusercontent.com/u/2325337?v=4",
+      "profile": "https://github.com/mboettcher",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "contributorsPerLine": 7,

README.md

@@ -616,6 +616,7 @@ Thanks goes to these people ([emoji key][emojis]):
     <td align="center"><a href="https://www.akashshyam.online/"><img src="https://avatars.githubusercontent.com/u/56759828?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Akash Shyam</b></sub></a><br /><a href="https://github.com/testing-library/react-testing-library/issues?q=author%3Aakashshyamdev" title="Bug reports">🐛</a></td>
     <td align="center"><a href="https://hen.ne.ke"><img src="https://avatars.githubusercontent.com/u/4312191?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Fabian Meumertzheim</b></sub></a><br /><a href="https://github.com/testing-library/react-testing-library/commits?author=fmeum" title="Code">💻</a> <a href="https://github.com/testing-library/react-testing-library/issues?q=author%3Afmeum" title="Bug reports">🐛</a></td>
     <td align="center"><a href="https://github.com/Nokel81"><img src="https://avatars.githubusercontent.com/u/8225332?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Sebastian Malton</b></sub></a><br /><a href="https://github.com/testing-library/react-testing-library/issues?q=author%3ANokel81" title="Bug reports">🐛</a> <a href="https://github.com/testing-library/react-testing-library/commits?author=Nokel81" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/mboettcher"><img src="https://avatars.githubusercontent.com/u/2325337?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Martin Böttcher</b></sub></a><br /><a href="https://github.com/testing-library/react-testing-library/commits?author=mboettcher" title="Code">💻</a></td>
   </tr>
 </table>