Use docs.gitea.com instead of docs.gitea.io (#26739)

docs/content/administration/customizing-gitea.en-us.md

@@ -36,7 +36,7 @@ Application settings can be found in file `CustomConf` which is by default,
 Again `gitea help` will allow you review this variable and you can override it using the
 `--config` option on the `gitea` binary.
 
-- [Quick Cheat Sheet](https://docs.gitea.io/en-us/config-cheat-sheet/)
+- [Quick Cheat Sheet](administration/config-cheat-sheet.md)
 - [Complete List](https://github.com/go-gitea/gitea/blob/main/custom/conf/app.example.ini)
 
 If the `CustomPath` folder can't be found despite checking `gitea help`, check the `GITEA_CUSTOM`
@@ -44,7 +44,7 @@ environment variable; this can be used to override the default path to something
 `GITEA_CUSTOM` might, for example, be set by an init script. You can check whether the value
 is set under the "Configuration" tab on the site administration page.
 
-- [List of Environment Variables](https://docs.gitea.io/en-us/environment-variables/)
+- [List of Environment Variables](administration/environment-variables.md)
 
 **Note:** Gitea must perform a full restart to see configuration changes.
 
@@ -84,7 +84,7 @@ for C++ repositories, we want to replace `options/gitignore/C++`. To do this, a
 must be placed in `$GITEA_CUSTOM/options/gitignore/C++` (see about the location of the `CustomPath`
 directory at the top of this document).
 
-Every single page of Gitea can be changed. Dynamic content is generated using [go templates](https://golang.org/pkg/html/template/),
+Every single page of Gitea can be changed. Dynamic content is generated using [go templates](https://pkg.go.dev/html/template),
 which can be modified by placing replacements below the `$GITEA_CUSTOM/templates` directory.
 
 To obtain any embedded file (including templates), the [`gitea embedded` tool](administration/cmd-embedded.md) can be used. Alternatively, they can be found in the [`templates`](https://github.com/go-gitea/gitea/tree/main/templates) directory of Gitea source (Note: the example link is from the `main` branch. Make sure to use templates compatible with the release you are using).
@@ -108,7 +108,7 @@ just place it under your "$GITEA_CUSTOM/public/assets/" directory (for instance
 To match the current style, the link should have the class name "item", and you can use `{{AppSubUrl}}` to get the base URL:
 `<a class="item" href="{{AppSubUrl}}/assets/impressum.html">Impressum</a>`
 
-For more information, see [Adding Legal Pages](https://docs.gitea.io/en-us/adding-legal-pages).
+For more information, see [Adding Legal Pages](administration/adding-legal-pages.md).
 
 You can add new tabs in the same way, putting them in `extra_tabs.tmpl`.
 The exact HTML needed to match the style of other tabs is in the file
@@ -371,10 +371,10 @@ A full list of supported emoji's is at [emoji list](https://gitea.com/gitea/gite
 ## Customizing the look of Gitea
 
 The default built-in themes are `gitea` (light), `arc-green` (dark), and `auto` (chooses light or dark depending on operating system settings).
-The default theme can be changed via `DEFAULT_THEME` in the [ui](https://docs.gitea.io/en-us/config-cheat-sheet/#ui-ui) section of `app.ini`.
+The default theme can be changed via `DEFAULT_THEME` in the [ui](administration/config-cheat-sheet.md#ui-ui) section of `app.ini`.
 
 Gitea also has support for user themes, which means every user can select which theme should be used.
-The list of themes a user can choose from can be configured with the `THEMES` value in the [ui](https://docs.gitea.io/en-us/config-cheat-sheet/#ui-ui) section of `app.ini`.
+The list of themes a user can choose from can be configured with the `THEMES` value in the [ui](administration/config-cheat-sheet.md#ui-ui) section of `app.ini`.
 
 To make a custom theme available to all users: