Updates the docs structure, navigation etc to be easier + better suited
for showing Nx technology support beyond just TS.
**Notes:**
- API (`/nx-api`) tab is removed from the navigation (i.e. menu bar),
but pages still remain for now until we update references in `*.md`
files.
- Redirects are set up `/nx-api` to go to their respect new location
e.g. `/technologies` or `/reference/core-api`
- Old URLs still exist in the sitemap for now, but majority of them will
be redirected -- a follow-up PR can remove them.
**Preview:**
https://nx-dev-git-nx-dev-polyglot-docs-restructure-nrwl.vercel.app/docs
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Co-authored-by: Jack Hsu <jack.hsu@gmail.com>
This PR removes installation instructions for Nx < 18 since it has
fallen out of support window. Users can always `npm install <plugin>` as
usual if they are on an unsupported Nx version, but the docs will assume
`nx add` moving forward.
The changes are on the plugin overview page:
https://nx-dev-git-docs-remove-nx-pre-18-install-nrwl.vercel.app/nx-api
