* Remove `jekyll-default-layout` plugin
* Move docs/navigation-structure to docs/navigation
* Fix uses of line-nos in md files
* Update CHANGELOG.md
---------
Co-authored-by: Matt Wang <matt@matthewwang.me>
This PR is motivated from https://github.com/just-the-docs/just-the-docs/pull/1259#issuecomment-1655899503. It adds a new workflow (`CI / Validate HTML (3.1)`) that validates the output of `bundle exec jekyll build`. It does this with two separate tools:
1. The [`html5validator-action`](https://github.com/Cyb3r-Jak3/html5validator-action), which is a wrapper (Docker image + argument forwarding) around the [Nu HTML checker](https://github.com/validator/validator), which is what is used by the [W3C markup validation service](https://validator.w3.org/)
2. [`html-proofer`](https://github.com/gjtorikian/html-proofer), which performs auxiliary checks on the validity of script, image, and link *values*, but not the markup itself
- note: prior versions of `html-proofer` did use nokogiri to also validate HTML, but the author has elected to remove that feature in versions 4+
I then fix a few issues that are flagged by these tools. I'll split this into,
**changes affecting users**:
- strictly incorrect: in `_layouts/minimal.html`, a `<div>` had duplicate `id`s. I've removed the incorrect one, which is related to...
- semantically wrong (but not technically incorrect): in both `minimal` and `default` layouts, we had two `<div>` tags with `id="main-content-wrap"`. These don't do anything; the associated styling is with the *class* `main-content-wrap`. I've elected to remove these `id`s to avoid confusion and keep the layouts in sync; however, **this is technically a breaking change**
- observe that `#main-content` is used for the "skip to main content" feature, which I missed in an earlier iteration of this PR
**changes affecting only our documentation**
- a broken link to mermaid docs (I've changed it to a valid one)
- an incorrectly-specified `aux_link` to our own repository
- various links that point to the bare URL `another-page`, which is clearly invalid; I've changed these to point to our homepage
- an incorrect header link
- various links to `http://example.com`, which I've changed to point to our homepage
- an incorrect link to `@flyx`'s profile for the AsciiDoctor gist
- a handful of (otherwise-valid) `http` links that should be `https`: the lunr docs, and patrick's personal website
The commit history shows the Nu validator flagging issues in CI properly in commits [4128b23](4128b23ef2) and [3527220](35272203ba).
## relevant configuration
- I exclude `github.com` URLs from external link checks with `html-proofer`. This is because GitHub does not like it when we ping too frequently, and rate limits us, which in turn provides many false positives. This is aligned with their documentation, which uses this ignore.
- I've pinned the hash for the 3rd-party action that wraps the W3C markup validation service. This aligns with #1148, but means that we'll have to keep an eye on it for updates.
In touching up the migration guide, I noticed that many of our documentation site links are broken! For example, on the homepage, this link:
<img width="782" alt="screenshot of homepage; code snippet is in next block" src="https://user-images.githubusercontent.com/14893287/210462690-31aa7bf5-dd79-4e8f-a3c5-1213e73771c4.png">
which has the following href
```code
<a href="/just-the-docs/just-the-docs/CHANGELOG/">the CHANGELOG</a>
```
duplicates the `baseurl` twice. There are 14 such broken links across the site. Each link duplicates the `baseurl` and `link` tags, which has since been resolved with links being relative by default (there's a set of PRs that document this - I can't find the exact paper trail right now).
To resolve this, I:
- find and replace site-wide `{{ site.baseurl }}{% link` with `{% link`
- tested each link, which now works properly locally *and* on the deploy preview
I'm surprised we didn't catch this earlier! I also could be missing something else, in which case feedback on this PR is certainly welcome.
