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.

docs/content/doc/advanced/config-cheat-sheet.zh-cn.md

@@ -17,6 +17,8 @@ menu:
 
 这是针对Gitea配置文件的说明，你可以了解Gitea的强大配置。需要说明的是，你的所有改变请修改 `custom/conf/app.ini` 文件而不是源文件。所有默认值可以通过 [app.example.ini](https://github.com/go-gitea/gitea/blob/master/custom/conf/app.example.ini) 查看到。如果你发现 `%(X)s` 这样的内容，请查看 [ini](https://github.com/go-ini/ini/#recursive-values) 这里的说明。标注了 :exclamation: 的配置项表明除非你真的理解这个配置项的意义，否则最好使用默认值。
 
+{{< toc >}}
+
 ## Overall (`DEFAULT`)
 
 - `APP_NAME`: 应用名称，改成你希望的名字。

docs/content/doc/advanced/customizing-gitea.en-us.md

@@ -45,6 +45,10 @@ environment variable; this can be used to override the default path to something
 
 **Note:** Gitea must perform a full restart to see configuration changes.
 
+# Table of Contents
+
+{{< toc >}}
+
 ## Serving custom public files
 
 To make Gitea serve custom public files (like pages and images), use the folder

docs/content/doc/advanced/logging-documentation.en-us.md

@@ -17,6 +17,8 @@ menu:
 
 The logging framework has been revamped in Gitea 1.9.0.
 
+{{< toc >}}
+
 ## Log Groups
 
 The fundamental thing to be aware of in Gitea is that there are several

docs/content/doc/advanced/mail-templates-us.md

@@ -21,6 +21,8 @@ Gitea has an internal template that serves as default in case there's no custom
 
 Custom templates are loaded when Gitea starts. Changes made to them are not recognized until Gitea is restarted again.
 
+{{< toc >}}
+
 ## Mail notifications supporting templates
 
 Currently, the following notification events make use of templates:
@@ -235,11 +237,11 @@ Please check [Gitea's logs](https://docs.gitea.io/en-us/logging-configuration/)
 
 This template produces something along these lines:
 
-#### Subject
+### Subject
 
 > [mike/stuff] @rhonda commented on pull request #38: New color palette
 
-#### Mail body
+### Mail body
 
 > [@rhonda](#) (Rhonda Myers) updated [mike/stuff#38](#).
 >