upgrade docusaurus

[jquense]

does what it says!

[kyletsang]

Some observations:

• Minor alignment issue for the home icon on the new breadcrumbs on each page
• Vanilla button styling isn't working on the first couple examples on the button page. Looks like the className prop is no longer propagating from mdx to live code block
• In the modal stacking example (http://localhost:3000/ui/Modal#modal-stacking), there's an error from emotion TypeError: Failed to resolve module specifier '@emotion/styled'
• In the overlay animation example (http://localhost:3000/ui/Overlay#animations), there's an error TypeError: Failed to resolve module specifier 'react-transition-group/Transition'
• The portal example doesn't render. Looks like this needs to be embedded into a function now
• Error in the waypoint hook example (http://localhost:3000/ui/Waypoint#usewaypoint): TypeError: Failed to resolve module specifier '@restart/ui/useWaypoint'
• Error in the useRootClose hook docs (http://localhost:3000/ui/useRootClose). Same as portal, needs to be rendered in a function now
• Error here: http://localhost:3000/ui/transitions#transition-component
• Imperative custom transitions animation is kinda janky on dismiss. Not sure if it was like this before. Also needs some padding

Random note not related to this PR, but I noticed the docs mention the transition prop accepts a RTG v2-compatible component. Should probably bump to v4-compatible.

[jquense]

I think i fixed most/all things, can follow up as needed 👍