html-proofer options changed, the command had to be updated.

The build also failed with an error, which was resolved by simply
updating to fedora 37 utility container with latest dependencies.

Sneaked my domain change in there. Pssst.

Fix not setting the locale before issuing the html-proofer command.

No shell files in this repository.

This should significantly speed up the CI pipeline, as we don't have to
build the quite messy utility container every time.

Actually the build will attempt to build the utility container stage as
we can't skip it but it is instructed to start off the uploaded utility
image from the 'utility' stage.

Allows running some targets contained in a special utility container
defined in Containerfile. This is done to contain (haha) the dependency
footprint of the targets on the host system.

The htmlproofer is setup in a ruby alpine container on each run of 'make
doc-check' and 'make doc'. This could be improved, by building the
container before using it form a provided Containerfile so the container
engine can cache the build result.

The spellchecker mdspell is nodejs based which adds nodejs to the
dependencies for now.

Apparently hugo needs git but does not pull it in as dependency.

At the time of commit it does not work to use a remote include when the
included project lives on the same git instance.