docs: add @aganglada as a contributor (#323)

Author: allcontributors[bot]

.all-contributorsrc

@@ -153,7 +153,8 @@
       "profile": "https://aganglada.com",
       "contributions": [
         "code",
-        "doc"
+        "doc",
+        "test"
       ]
     },
     {

README.md

@@ -157,7 +157,7 @@ Thanks goes to these people ([emoji key][emojis]):
     <td align="center"><a href="http://brainbox.cz/"><img src="https://avatars1.githubusercontent.com/u/762095?v=4" width="100px;" alt=""/><br /><sub><b>Michal Kočárek</b></sub></a><br /><a href="https://github.com/testing-library/testing-playground/commits?author=michal-kocarek" title="Code">💻</a> <a href="#ideas-michal-kocarek" title="Ideas, Planning, & Feedback">🤔</a></td>
   </tr>
   <tr>
-    <td align="center"><a href="https://aganglada.com"><img src="https://avatars0.githubusercontent.com/u/922348?v=4" width="100px;" alt=""/><br /><sub><b>Alejandro Garcia Anglada</b></sub></a><br /><a href="https://github.com/testing-library/testing-playground/commits?author=aganglada" title="Code">💻</a> <a href="https://github.com/testing-library/testing-playground/commits?author=aganglada" title="Documentation">📖</a></td>
+    <td align="center"><a href="https://aganglada.com"><img src="https://avatars0.githubusercontent.com/u/922348?v=4" width="100px;" alt=""/><br /><sub><b>Alejandro Garcia Anglada</b></sub></a><br /><a href="https://github.com/testing-library/testing-playground/commits?author=aganglada" title="Code">💻</a> <a href="https://github.com/testing-library/testing-playground/commits?author=aganglada" title="Documentation">📖</a> <a href="https://github.com/testing-library/testing-playground/commits?author=aganglada" title="Tests">⚠️</a></td>
     <td align="center"><a href="https://github.com/ddehart"><img src="https://avatars3.githubusercontent.com/u/901215?v=4" width="100px;" alt=""/><br /><sub><b>ddehart</b></sub></a><br /><a href="https://github.com/testing-library/testing-playground/commits?author=ddehart" title="Code">💻</a> <a href="https://github.com/testing-library/testing-playground/commits?author=ddehart" title="Tests">⚠️</a></td>
     <td align="center"><a href="https://balavishnuvj.com/?utm_source=github"><img src="https://avatars3.githubusercontent.com/u/13718688?v=4" width="100px;" alt=""/><br /><sub><b>Balavishnu V J</b></sub></a><br /><a href="https://github.com/testing-library/testing-playground/commits?author=balavishnuvj" title="Code">💻</a></td>
   </tr>