Fix (make-)issuer.nix file name inconsistency

See merge request !84

Discern make-issuer.nix from issuer.nix better.

Update branch by merging @jcalderone's feedback on local-dev-env-2.

Add local development network Vagrantfile and Documentation

See merge request !81

... if other hypervisors are installed as well.

Co-Authored-By: Jean-Paul Calderone <jean-paul@privatestorage.io>

This updates this MR to the latest base branch (develop) and also
is an experiment on what happens when I merge instead of rebase to
update MRs.

Create documentation artifacts

See merge request !80

Using a copy of the docs artifacts for packing up
should not exhibit the problems from earlier.

Remove user documentation

See merge request !79

Make GitLab CI choose the right build runner

See merge request opensource/PrivateStorageio!78