docs: add kwboyd as a contributor (#536)

Author: allcontributors[bot]

.all-contributorsrc

@@ -870,6 +870,15 @@
         "code",
         "test"
       ]
+    },
+    {
+      "login": "kwboyd",
+      "name": "Kate W. Boyd",
+      "avatar_url": "https://avatars0.githubusercontent.com/u/13855750?v=4",
+      "profile": "http://kwboyd.com",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "repoHost": "https://github.com"

README.md

@@ -244,6 +244,7 @@ Thanks goes to these people ([emoji key][emojis]):
     <td align="center"><a href="https://github.com/apalaniuk"><img src="https://avatars1.githubusercontent.com/u/17710124?v=4" width="100px;" alt=""/><br /><sub><b>Adam Palaniuk</b></sub></a><br /><a href="https://github.com/testing-library/dom-testing-library/commits?author=apalaniuk" title="Code">💻</a> <a href="https://github.com/testing-library/dom-testing-library/commits?author=apalaniuk" title="Tests">⚠️</a></td>
     <td align="center"><a href="https://github.com/Yama-Tomo"><img src="https://avatars0.githubusercontent.com/u/4970917?v=4" width="100px;" alt=""/><br /><sub><b>Yama-Tomo</b></sub></a><br /><a href="https://github.com/testing-library/dom-testing-library/commits?author=Yama-Tomo" title="Code">💻</a> <a href="https://github.com/testing-library/dom-testing-library/commits?author=Yama-Tomo" title="Tests">⚠️</a></td>
     <td align="center"><a href="https://github.com/airjp73"><img src="https://avatars2.githubusercontent.com/u/25882770?v=4" width="100px;" alt=""/><br /><sub><b>Aaron Pettengill</b></sub></a><br /><a href="https://github.com/testing-library/dom-testing-library/commits?author=airjp73" title="Code">💻</a> <a href="https://github.com/testing-library/dom-testing-library/commits?author=airjp73" title="Tests">⚠️</a></td>
+    <td align="center"><a href="http://kwboyd.com"><img src="https://avatars0.githubusercontent.com/u/13855750?v=4" width="100px;" alt=""/><br /><sub><b>Kate W. Boyd</b></sub></a><br /><a href="https://github.com/testing-library/dom-testing-library/commits?author=kwboyd" title="Code">💻</a></td>
   </tr>
 </table>