add GuoCheng24 as a contributor for content (#2871)

* update README.md

* update .all-contributorsrc

* update website/src/pages/contributors.astro

---------

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

.all-contributorsrc

@@ -3597,6 +3597,15 @@
       "contributions": [
         "doc"
       ]
+    },
+    {
+      "login": "GuoCheng24",
+      "name": "Guo Cheng",
+      "avatar_url": "https://avatars.githubusercontent.com/u/224264187?v=4",
+      "profile": "https://github.com/GuoCheng24",
+      "contributions": [
+        "content"
+      ]
     }
   ]
 }