VuePress docs

[marshallswain]

This moves the docs from the old feathers-plus/docs repository directly into this project.

• Use VuePress
• Dark theme (automatically follows the dark mode setting for browsers and operating systems which support it)
• Move hooks to their own page.
• Move utilities to their own page.
• Replace hooksApi utils with actual markdown tables.
• Replace hooksApiFootnote utils with actual content
• Remove recent deprecations
• Update docs for getByDot, setByDot, deleteByDot, and any others that have recently changed.

[daffl]

The above action items have now been done. Other things left to do:

• Update softDelete docs with new softDelete
• Use Feathers docs Vuepress template (it doesn't have a dark mode version yet but it would be great to have one)
• Set up subdomain and Netlify deploy

[daffl]

Going to merge this since it's pretty much ready to go for now and I'd like to deploy a build. Other docs should go with their respective or separate PRs.