Adds instructions for using the tab bar, moves tab layout docs to new
location with redirect, adds instructions for magnifying a block, cleans
up intro text.
Also adds missing global keybindings.
Also reorders docs in the sidebar, introduces new mechanisms for
indicating how an img should float in a document, and adds a `<div
style="clear: both">` before every heading.
## Summary
We are moving our docsite to this repo for better coordination.
## What's changed?
- The docsite codebase is now in docs/
- The docsite will replace storybook as the published GitHub Pages site
for this repo
- Storybook will now be hosted at https://docs.waveterm.dev/storybook
- A new CI workflow will validate any changes to Storybook or the
docsite
- A combined CD workflow will build and deploy Storybook and the docsite
as a single artifact
- The Build Helper workflow will now build an embedded version of the
docsite before building the app, ensuring the docsite version it has is
always the latest
