chore: add contributors to README.md

.all-contributorsrc

@@ -0,0 +1,37 @@
+{
+  "projectName": "testing-playground",
+  "projectOwner": "smeijer",
+  "repoType": "github",
+  "repoHost": "https://github.com",
+  "files": [
+    "README.md"
+  ],
+  "imageSize": 100,
+  "commit": false,
+  "commitConvention": "angular",
+  "contributors": [
+    {
+      "login": "smeijer",
+      "name": "Stephan Meijer",
+      "avatar_url": "https://avatars1.githubusercontent.com/u/1196524?v=4",
+      "profile": "https://github.com/smeijer",
+      "contributions": [
+        "ideas",
+        "code",
+        "infra",
+        "maintenance"
+      ]
+    },
+    {
+      "login": "marcosvega91",
+      "name": "Marco Moretti",
+      "avatar_url": "https://avatars2.githubusercontent.com/u/5365582?v=4",
+      "profile": "https://github.com/marcosvega91",
+      "contributions": [
+        "code",
+        "test"
+      ]
+    }
+  ],
+  "contributorsPerLine": 7
+}

README.md

@@ -1,5 +1,11 @@
 # Testing-Playground ([demo])
 
+<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
+
+[![All Contributors](https://img.shields.io/badge/all_contributors-2-orange.svg?style=flat-square)](#contributors-)
+
+<!-- ALL-CONTRIBUTORS-BADGE:END -->
+
 **Playground for [testing-library/dom]**
 
 ![screenshot of unimported results](./docs/testing-playground-com.gif)
@@ -11,11 +17,35 @@ Testing-Playground provides you with direct feedback. Trying to visualize the di
 [testing-library/dom]: https://testing-library.com/docs/dom-testing-library/example-intro
 [demo]: https://testing-playground.com
 
-# Roadmap
+## Roadmap
 
 Future ideas are maintained in the [roadmap]. Please use the [issue tracker] to discuss any questions or suggestions you have.
 
 Every section in the roadmap is accompanied by one or more issues. Contributions are most welcome!
 
+## Contributors
+
+Thanks goes to these people ([emoji key][emojis]):
+
+<!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
+<!-- prettier-ignore-start -->
+<!-- markdownlint-disable -->
+<table>
+  <tr>
+    <td align="center"><a href="https://github.com/smeijer"><img src="https://avatars1.githubusercontent.com/u/1196524?v=4" width="100px;" alt=""/><br /><sub><b>Stephan Meijer</b></sub></a><br /><a href="#ideas-smeijer" title="Ideas, Planning, & Feedback">🤔</a> <a href="https://github.com/smeijer/testing-playground/commits?author=smeijer" title="Code">💻</a> <a href="#infra-smeijer" title="Infrastructure (Hosting, Build-Tools, etc)">🚇</a> <a href="#maintenance-smeijer" title="Maintenance">🚧</a></td>
+    <td align="center"><a href="https://github.com/marcosvega91"><img src="https://avatars2.githubusercontent.com/u/5365582?v=4" width="100px;" alt=""/><br /><sub><b>Marco Moretti</b></sub></a><br /><a href="https://github.com/smeijer/testing-playground/commits?author=marcosvega91" title="Code">💻</a> <a href="https://github.com/smeijer/testing-playground/commits?author=marcosvega91" title="Tests">⚠️</a></td>
+  </tr>
+</table>
+
+<!-- markdownlint-enable -->
+<!-- prettier-ignore-end -->
+
+<!-- ALL-CONTRIBUTORS-LIST:END -->
+
+This project follows the [all-contributors][all-contributors] specification.
+Contributions of any kind welcome!
+
 [roadmap]: https://github.com/smeijer/testing-playground/blob/master/ROADMAP.md
 [issue tracker]: https://github.com/smeijer/testing-playground/issues
+[all-contributors]: https://github.com/all-contributors/all-contributors
+[emojis]: https://github.com/all-contributors/all-contributors#emoji-key