docs: add versioned docs

[awphi]

Changes

• Bumps us to the latest version of ADP; 0.6.0 which comes with
  • New styling
  • Support for versioned docs
• Adds automated versioned docs releasing:
  • The main pain point of the docs versioning is it requires hard-coding a list of refs we want to host docs for in the repo. This felt like a lot of manual work so this adds a little script to generate the relevant config for the last 5 major releases.
  • Runs said script prior to publishing to staging. As part of this, the script also supports passing --include-head so we can preview a 'Latest' version in staging
  • Adds a compose.preview.yaml compose project to preview the production/staging version of the docs locally. I don't foresee this being desperately useful but it does provide some level of confidence before deploying.

I'm keen for feedback if we think the automated versions generation is the right way to go + if we need the local production preview project at all. Lmk!

Checklist

• 🤖 This change is covered by tests as required.
• 🤹 All required manual testing has been performed.
• 📖 All documentation updates are complete.

[muchzill4]

We need to push latest major, not major.0.0. I.e.: 7.5.2 > 7.0.0.

[muchzill4]

has_docs_config_at_ref() {
  git cat-file -e "$1:docs/docs-config.json" 2>/dev/null
}

And maybe:

last_five_major_release_tags=$(
  gh release list \
    --exclude-drafts --exclude-pre-releases \
    --limit 1000 --json tagName |
    jq '[.[] | select(.tagName | test("^v?[0-9]+\\.0\\.0$"))][:5][].tagName'
)

[awphi]

As discussed, have hard-coded a minimum major version to search from + made it fetch all latest releases from each major prefix