docs: add AnnikaCodes as a contributor (rust-lang#557)

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

.all-contributorsrc

@@ -601,6 +601,15 @@
         "code"
       ]
     },
+    {
+      "login": "AnnikaCodes",
+      "name": "Annika",
+      "avatar_url": "https://avatars3.githubusercontent.com/u/56906084?v=4",
+      "profile": "https://github.com/AnnikaCodes",
+      "contributions": [
+        "review"
+      ]
+    },
     {
       "login": "darnuria",
       "name": "Axel Viala",

README.md

@@ -229,6 +229,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
     <td align="center"><a href="https://ryanpcmcquen.org"><img src="https://avatars3.githubusercontent.com/u/772937?v=4" width="100px;" alt=""/><br /><sub><b>Ryan McQuen</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=ryanpcmcquen" title="Code">💻</a></td>
   </tr>
   <tr>
+    <td align="center"><a href="https://github.com/AnnikaCodes"><img src="https://avatars3.githubusercontent.com/u/56906084?v=4" width="100px;" alt=""/><br /><sub><b>Annika</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/pulls?q=is%3Apr+reviewed-by%3AAnnikaCodes" title="Reviewed Pull Requests">👀</a></td>
     <td align="center"><a href="https://darnuria.eu"><img src="https://avatars1.githubusercontent.com/u/2827553?v=4" width="100px;" alt=""/><br /><sub><b>Axel Viala</b></sub></a><br /><a href="https://github.com/rust-lang/rustlings/commits?author=darnuria" title="Code">💻</a></td>
   </tr>
 </table>