While here, also add sub-headings to allow direct links with anchors
to the relevant section.

We can't install both types of plugins, so when SUFFIX= we need to
exclude "-devel".  Not the prettiest approach, but should do it in
99% of cases.

The changes show some things that need to be inspected...

Better to separate the branches right away

The migrations don't run because PHP isn't active.  That's an issue
of configd never being initialised, which we came to before so we
may need a bootstrap template for both php.ini files just in case.

Still stalls in template regeneration, needs some thinking.

squidclamav is unused.

... it masks the fact that we have a plugin in our config that does
not exist on all trees yet.  That shouldn't happen.

The `update' target has made several advances in the last months,
so that it can be used to collect new changes, switch to the correct
branch and also clone repositories as needed.