content: fix self hosting guide

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

Document 'd' shortcut for sprig, minor cleanups.

Add invisible metadata specification

fix: update sync meeting schedule

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

doc: fix off-by-one in node type spec

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

doc: fix small typos in active status spec

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

fix: link to toml directly

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

fix: restructure markdown to appease wiki

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

fix: add directory index page to specs

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

fix: attempt to fix spec link

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

Add expiration specification

Add twig extensions spec README

Add active-status spec

ci: disable doc deploy until hosting is configured

Add MkDocs build manifest

This is a simple manifest that spins up an Arch VM, installs Material
for MkDocs [1], builds the site, then pushes it to a web server. The
port, user, server IP address, and webroot path are specified using
environment variables.

[1]: https://squidfunk.github.io/mkdocs-material/
[2]: https://www.mkdocs.org/

delete index of specs because it's unnecessary

modify page titles

- Index page will show up under the site name (Arbor Chat) and having
  the title of the page the same as the site is a bit repetitive.
- Remove "Specification" from the titles of forest and sprout docs for
  the same reason
- Remove "Arbor" from technical overview for the same

reorganise and merge guides

- The Getting Started and Hosting an Arbor relay guides have been moved
  to the guide/ directory
- getting-started.md now includes a note about wisteria being deprecated
  as well as the usage guide at the bottom in case someone is interested
  in picking it up
- getting-started-cli.md has been deleted (merged with main)

add support for new vale

Something in a recent update broke one of our rules and that has been
corrected in this commit.

add contributing doc and mention vale linting