Added Table of Contents to long documentation pages (#13890)

* Redo #13836 with new shortcode
(https://gitea.com/gitea/theme/pulls/90)

* add Api Usage

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -31,6 +31,8 @@ Values containing `#` or `;` must be quoted using `` ` `` or `"""`.
 
 **Note:** A full restart is required for Gitea configuration changes to take effect.
 
+{{< toc >}}
+
 ## Overall (`DEFAULT`)
 
 - `APP_NAME`: **Gitea: Git with a cup of tea**: Application name, used in the page title.