docs: add sixth as a contributor (#375)

* docs: update README.md

* docs: update .all-contributorsrc

.all-contributorsrc

@@ -357,6 +357,15 @@
         "code",
         "test"
       ]
+    },
+    {
+      "login": "sixth",
+      "name": "sixth",
+      "avatar_url": "https://avatars3.githubusercontent.com/u/11591445?v=4",
+      "profile": "https://github.com/sixth",
+      "contributions": [
+        "doc"
+      ]
     }
   ],
   "contributorsPerLine": 7,

README.md

@@ -113,6 +113,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
     <td align="center"><a href="https://noplanman.ch"><img src="https://avatars3.githubusercontent.com/u/9423417?v=4" width="100px;" alt="Armando Lüscher"/><br /><sub><b>Armando Lüscher</b></sub></a><br /><a href="https://github.com/containrrr/watchtower/commits?author=noplanman" title="Documentation">📖</a></td>
     <td align="center"><a href="https://github.com/rjbudke"><img src="https://avatars2.githubusercontent.com/u/273485?v=4" width="100px;" alt="Ryan Budke"/><br /><sub><b>Ryan Budke</b></sub></a><br /><a href="https://github.com/containrrr/watchtower/commits?author=rjbudke" title="Documentation">📖</a></td>
     <td align="center"><a href="http://kaloyan.raev.name"><img src="https://avatars2.githubusercontent.com/u/468091?v=4" width="100px;" alt="Kaloyan Raev"/><br /><sub><b>Kaloyan Raev</b></sub></a><br /><a href="https://github.com/containrrr/watchtower/commits?author=kaloyan-raev" title="Code">💻</a> <a href="https://github.com/containrrr/watchtower/commits?author=kaloyan-raev" title="Tests">⚠️</a></td>
+    <td align="center"><a href="https://github.com/sixth"><img src="https://avatars3.githubusercontent.com/u/11591445?v=4" width="100px;" alt="sixth"/><br /><sub><b>sixth</b></sub></a><br /><a href="https://github.com/containrrr/watchtower/commits?author=sixth" title="Documentation">📖</a></td>
   </tr>
 </table>