This macro allows embedding TOML data into the docs,
and showing it in a tab that has both the TOML and JSON
representation of that data.
It works by executing the toml2jsonc helper that was added
in an earlier commit.
There's some machinery here to compile that utility to run
in the context of the mkdocs docker image; that works
locally, let's see how well it works in CI!
Usage is simple; before:
```toml
["something"]
foo = "bar"
```
after:
{% call toml_data() %}
["something"]
foo = "bar"
{% endcall %}
The first page to get switched over to this is https://docs.kumomta.com/tutorial/configuring_kumomta/
refs: https://github.com/KumoCorp/kumomta/issues/212
It's a PITA to bootstrap the docker daemon, and pointing it to the host
daemon to sidestep all that is insecure and should not be trusted in a
public repo like this.
So, let's just try podman for this: it doesn't need a daemon and
doesn't need any special privs.
Wez Furlong