docs: add Edit this page (#21981)

Update theme to support `Edit this page`:
https://gitea.com/gitea/theme/pulls/116

Screenshot:
![Edit this
page](https://user-images.githubusercontent.com/76462613/205257167-d6039d0c-c913-4ebc-98c1-834aece4b5e9.png)

Signed-off-by: Xinyu Zhou <[email protected]>
Co-authored-by: John Olheiser <[email protected]>
Co-authored-by: techknowlogick <[email protected]>
Co-authored-by: Lunny Xiao <[email protected]>

Author: 4 people

docs/config.yaml

@@ -23,6 +23,8 @@ params:
   goVersion: 1.19
   minNodeVersion: 14
   search: nav
+  repo: "https://github.com/go-gitea/gitea"
+  docContentPath: "docs/content"
 
 outputs:
   home: