docs: add Belco90 as a contributor (#278)

* docs: update README.md

* docs: update .all-contributorsrc


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

Author: superT999

.all-contributorsrc

@@ -350,6 +350,15 @@
       "contributions": [
         "doc"
       ]
+    },
+    {
+      "login": "Belco90",
+      "name": "Mario Beltrán Alarcón",
+      "avatar_url": "https://avatars1.githubusercontent.com/u/2677072?v=4",
+      "profile": "https://mario.dev",
+      "contributions": [
+        "doc"
+      ]
     }
   ],
   "contributorsPerLine": 7,

README.md

@@ -82,6 +82,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
     <td align="center"><a href="https://github.com/wdoug"><img src="https://avatars3.githubusercontent.com/u/5432102?v=4" width="100px;" alt="Will Douglas"/><br /><sub><b>Will Douglas</b></sub></a><br /><a href="https://github.com/testing-library/testing-library-docs/commits?author=wdoug" title="Documentation">📖</a></td>
     <td align="center"><a href="https://velog.io/@head"><img src="https://avatars0.githubusercontent.com/u/40166539?v=4" width="100px;" alt="Head"/><br /><sub><b>Head</b></sub></a><br /><a href="https://github.com/testing-library/testing-library-docs/commits?author=HTMLhead" title="Documentation">📖</a></td>
     <td align="center"><a href="https://github.com/mynar7"><img src="https://avatars0.githubusercontent.com/u/32332479?v=4" width="100px;" alt="Lee"/><br /><sub><b>Lee</b></sub></a><br /><a href="https://github.com/testing-library/testing-library-docs/commits?author=mynar7" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://mario.dev"><img src="https://avatars1.githubusercontent.com/u/2677072?v=4" width="100px;" alt="Mario Beltrán Alarcón"/><br /><sub><b>Mario Beltrán Alarcón</b></sub></a><br /><a href="https://github.com/testing-library/testing-library-docs/commits?author=Belco90" title="Documentation">📖</a></td>
   </tr>
 </table>