docs: add nstepien as a contributor (#557)

Author: allcontributors[bot]

.all-contributorsrc

@@ -899,6 +899,15 @@
         "code",
         "test"
       ]
+    },
+    {
+      "login": "nstepien",
+      "name": "Nicolas Stepien",
+      "avatar_url": "https://avatars0.githubusercontent.com/u/567105?v=4",
+      "profile": "https://github.com/nstepien",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "repoHost": "https://github.com"

README.md

@@ -248,6 +248,9 @@ Thanks goes to these people ([emoji key][emojis]):
     <td align="center"><a href="https://github.com/rahulchavan30"><img src="https://avatars2.githubusercontent.com/u/5296464?v=4" width="100px;" alt=""/><br /><sub><b>Rahul Suryakanth</b></sub></a><br /><a href="https://github.com/testing-library/dom-testing-library/commits?author=rahulchavan30" title="Code">💻</a> <a href="https://github.com/testing-library/dom-testing-library/commits?author=rahulchavan30" title="Tests">⚠️</a></td>
     <td align="center"><a href="https://jamie.tokyo"><img src="https://avatars0.githubusercontent.com/u/5964236?v=4" width="100px;" alt=""/><br /><sub><b>Jamie</b></sub></a><br /><a href="https://github.com/testing-library/dom-testing-library/commits?author=jamsinclair" title="Code">💻</a> <a href="https://github.com/testing-library/dom-testing-library/commits?author=jamsinclair" title="Tests">⚠️</a></td>
   </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/nstepien"><img src="https://avatars0.githubusercontent.com/u/567105?v=4" width="100px;" alt=""/><br /><sub><b>Nicolas Stepien</b></sub></a><br /><a href="https://github.com/testing-library/dom-testing-library/commits?author=nstepien" title="Code">💻</a></td>
+  </tr>
 </table>
 
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