doc: add summary top paragraph to hosting doc
doc: document how to set up an arbor relay
docs: fix markdown rendering of button list
update getting started guide

I went through the guide and updated portions to reflect UI changes and
make some of the process clearer. I also fixed the headings and ran the
file through Vale, correcting some of the errors and warnings.
integrate vale

This massive patch attemps to standardise out documentation. For those
unfamiliar with it, Vale is "a syntax-aware linter for prose built with
speed and extensibility in mind" [1]. I built on Vale's
implementation [2] of Google's style guide [3] with specifics for Arbor
and the vocabulary we've started using.

[1]: https://github.com/errata-ai/vale
[2]: https://github.com/errata-ai/Google
[3]: https://developers.google.com/style/

I didn't modify any of the docs that are already written so some of them
will have a ton of errors. Once Arbor's style has been reviewed and a
bit more polished, I'll go through and start implementing the
recommended changes. To that end, install Vale [1], run it on a few
files, and see what the output says. Feedback is welcome.

[1]: https://errata-ai.gitbook.io/vale/getting-started/installation
Add Sprig to project list
docs: fix typo
add new diagrams and update docs

I added the new diagrams and updated the docs to include them along with
an explanation of what's going on for the simpler overview.

I included the graphml files so they can be imported and edited/improve
later on but I don't know how they'll work in other programs; I created
them in yEd: yworks.com/products/yed

The dark diagrams have transparent backgrounds so they should be
suitable for any shade and the light diagrams are simply white. SVGs are
including for editing colors and exporting at various sizes.
move wisteria guide to separate doc
replace wisteria guide with one for sprig
make spec links relative

The previous links would lead to sourcehut's root and 404 but these should
lead to the correct locations.
Remove outdated implementation links.
docs: fix link to node encoding
docs: clarify node ID encoding and example
docs: define how to encode node IDs as strings
add missing word and use better link descriptor
normalize capitalization and correct spelling
normalize capitalization and link to twig
correct capitalization
replace "here" link text with better descriptors

Same as 8a82515
grammatical, spelling, and capitalisation changes

I corrected a few misspelled words, capitalised the first letter
of bullets and the words "Arbor" and "Forest" in a couple of
places, and added backticks around the sprout:// protocol string.