docs: updates to admin customization docs (#7493)

* updated admin docs

* re-add navigation and parameters sections

* update injection zones

* update cli scripts docs

* added list of injection zones

* add details about widget props

* restructure admin injection zones

www/apps/book/app/advanced-development/admin/page.mdx

@@ -4,19 +4,12 @@ export const metadata = {
 
 # {metadata.title}
 
-<Note type="soon">
-
-Admin customizations are coming soon.
-
-</Note>
-
 In the next chapters, you'll learn more about possible admin customizations.
 
 You can customize the admin dashboard by:
 
 - Adding new sections to existing pages using Widgets.
 - Adding new pages using UI Routes.
-- Adding new pages to the Settings section of the admin dashboard using Setting Pages.
 
 ---