[ui-library][docs] Folder structure sidebar on mobile

# Bug report - [x] I confirm this is a bug with Supabase, not with my own application. - [x] I confirm I have searched the [Docs](https://docs.supabase.com), GitHub [Discussions](https://github.com/supabase/supabase/discussions), and [Discord](https://discord.supabase.com). ## Describe the bug On mobile the "folder structure" section has the sidebar open all the time on mobile without an ability to collapse it. ## To Reproduce Steps to reproduce the behavior, please provide code snippets or a repository: 1. Go to https://supabase.com/ui/docs/infinite-query-hook on mobile 2. Scroll down to the folder structure and you should see the the same as the screenshot below ## Expected behavior it should at least be collapsible (missing sidebar trigger probably) ## Screenshots  ## System information - OS: iPhone 13 - Browser: **chrome**