📝 Document how to install packages on-demand in containers

[shnizzedy]

Related problem

Containers (especially when running as non-root and/or in Apptainer/Singularity) have a lot of read-only access, but sometimes devs need to install a package in a container without needing it added to the distribution image.

Proposed feature

Document how to do this in the dev docs

Acceptance criteria

• dev docs include how-to-install-a-package

Alternatives

No response

Additional context

No response