docs: Split features into new administration category (#1440)

* docs: Split features into new administration category

* docs: Add redirects for moved pages

web/src/lib/components/admin-page/settings/confirm-disable-login.svelte

@@ -12,7 +12,7 @@
 			<p class="text-md text-center">
 				To re-enable, use a
 				<a
-					href="https://immich.app/docs/features/server-commands"
+					href="https://immich.app/docs/administration/server-commands"
 					rel="noreferrer"
 					target="_blank"
 					class="underline"

web/src/lib/components/admin-page/settings/oauth/oauth-settings.svelte

@@ -111,7 +111,7 @@
 			<form autocomplete="off" on:submit|preventDefault class="flex flex-col mx-4 gap-4 py-4">
 				<p class="text-sm dark:text-immich-dark-fg">
 					For more details about this feature, refer to the <a
-						href="http://immich.app/docs/features/oauth#mobile-redirect-uri"
+						href="http://immich.app/docs/administration/oauth#mobile-redirect-uri"
 						class="underline"
 						target="_blank"
 						rel="noreferrer">docs</a