docs: add tf as a contributor (#268)

* docs: update README.md
* docs: update .all-contributorsrc

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

Author: allcontributors[bot]

.all-contributorsrc

@@ -483,6 +483,17 @@
         "code",
         "test"
       ]
+    },
+    {
+      "login": "tf",
+      "name": "Tim Fischbach",
+      "avatar_url": "https://avatars3.githubusercontent.com/u/26554?v=4",
+      "profile": "http://stderr.timfischbach.de",
+      "contributions": [
+        "code",
+        "test",
+        "ideas"
+      ]
     }
   ],
   "repoHost": "https://github.com",

README.md

@@ -1157,6 +1157,7 @@ Thanks goes to these people ([emoji key][emojis]):
     <td align="center"><a href="https://rubenmoya.dev"><img src="https://avatars3.githubusercontent.com/u/905225?v=4" width="100px;" alt=""/><br /><sub><b>Rubén Moya</b></sub></a><br /><a href="https://github.com/testing-library/jest-dom/commits?author=rubenmoya" title="Code">💻</a> <a href="https://github.com/testing-library/jest-dom/commits?author=rubenmoya" title="Tests">⚠️</a> <a href="https://github.com/testing-library/jest-dom/commits?author=rubenmoya" title="Documentation">📖</a></td>
     <td align="center"><a href="https://danielavalero.com/"><img src="https://avatars1.githubusercontent.com/u/1307954?v=4" width="100px;" alt=""/><br /><sub><b>Daniela Valero</b></sub></a><br /><a href="https://github.com/testing-library/jest-dom/commits?author=DanielaValero" title="Code">💻</a> <a href="https://github.com/testing-library/jest-dom/commits?author=DanielaValero" title="Tests">⚠️</a> <a href="https://github.com/testing-library/jest-dom/commits?author=DanielaValero" title="Documentation">📖</a></td>
     <td align="center"><a href="https://github.com/missilev"><img src="https://avatars1.githubusercontent.com/u/33201468?v=4" width="100px;" alt=""/><br /><sub><b>Vladislav Katsura</b></sub></a><br /><a href="https://github.com/testing-library/jest-dom/commits?author=missilev" title="Code">💻</a> <a href="https://github.com/testing-library/jest-dom/commits?author=missilev" title="Tests">⚠️</a></td>
+    <td align="center"><a href="http://stderr.timfischbach.de"><img src="https://avatars3.githubusercontent.com/u/26554?v=4" width="100px;" alt=""/><br /><sub><b>Tim Fischbach</b></sub></a><br /><a href="https://github.com/testing-library/jest-dom/commits?author=tf" title="Code">💻</a> <a href="https://github.com/testing-library/jest-dom/commits?author=tf" title="Tests">⚠️</a> <a href="#ideas-tf" title="Ideas, Planning, & Feedback">🤔</a></td>
   </tr>
 </table>