Add the `lightweight` tag to run jobs on the GitLab runners set up for
jobs that do not need large amounts of resources (max 2GB of RAM) and do
not need privileged containers.

The former makes jobs cheaper because they user smaller VM instance
types, the latter improves latency as there's no strong need to spin
separate VMs to keep each job isolated and existing instances can be
re-used instead.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

Try to speed up the single-threaded PDF generation by starting a process
for each CPU core.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

GitLab Pages only really handles a single branch for each project, so
forking is the best way to have the proposed pages be rendered and
published by Pages.

By setting `baseURL` from CI using `$CI_PAGES_URL` we can ensure that
links are set properly instead of always pointing at
https://www.apertis.org/ as that's quite confusing during reviews.

However, for the main project we don't want to use the default GitLab
pages address, but we want to have links using the official
https://www.apertis.org/ address: to the main project now sets
`$BASEURL` as a CI/CD variable to point at https://www.apertis.org/


while forked projects will use the default based on `$CI_PAGES_URL`.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

Apertis currently has a large number of concept documents on
designs.apertis.org. To improve branding, searchability and reduce
maintenance, it would be better to have all these documents under the
main website. One feature that the website is currently missing that is
provided on designs.a.o is PDF generation, which is used when reviewing
concepts with Bosch.

Carry over the PDF generation functionality from designs.a.o and
implement a mechanism for generating PDFs from the Hugo site on
www.apertis.org so that we can move documents over from designs.a.o
without loosing needed functionality.

To do this we will generate simplfied HTML documents, with the
extension `.pdf-in` when documents require this to be generated in
their frontmatter, for example to generate html and the simplified HTML
add:

    outputs = ["html", "pdf-in"]

The create-pdf script will be run for each of these via the CI pipeline
which will use a lightly modified version of the tooling used for
designs.a.o to create the PDF and place it back into the site.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

A wayward feature/bug in Hugo 0.63.1 results in the homepage being badly
formatted:

  https://github.com/gohugoio/hugo/issues/6805



This is rectified in 0.63.2, but the docker image for this does not exist
yet.

It seems that it is risky for us to depend on `latest` in the CI runner
as this can result in unpredictable issues with the website. As the
`stable` Hugo branch tracks the latest release, it wouldn't have helped us
in this instance (the issue was present in the latest release) and this
doesn't seemed to be tracked by the docker image registry.

Lock to version 0.62.2, we will have to update this more manually on a
regular basis.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>