docs: add mpdcampbell as a contributor for doc (#2444)

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

.all-contributorsrc

@@ -557,6 +557,15 @@
       "contributions": [
         "code"
       ]
+    },
+    {
+      "login": "mpdcampbell",
+      "name": "Michael Campbell",
+      "avatar_url": "https://avatars.githubusercontent.com/u/47434940?v=4",
+      "profile": "https://github.com/mpdcampbell",
+      "contributions": [
+        "doc"
+      ]
     }
   ],
   "contributorsPerLine": 7

README.md

@@ -272,6 +272,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
   </tr>
   <tr>
     <td align="center"><a href="https://github.com/you1996"><img src="https://avatars.githubusercontent.com/u/45292366?v=4?s=100" width="100px;" alt=""/><br /><sub><b>yossbg</b></sub></a><br /><a href="https://github.com/authelia/authelia/commits?author=you1996" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/mpdcampbell"><img src="https://avatars.githubusercontent.com/u/47434940?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Michael Campbell</b></sub></a><br /><a href="https://github.com/authelia/authelia/commits?author=mpdcampbell" title="Documentation">📖</a></td>
   </tr>
 </table>