Finish documenting the local BaseX installation guidelines

[bansp]

Temporarily a mess, but it's going to get fixed soon: https://github.com/clarin-eric/standards/wiki/BaseX-installation

[bansp]

This is now done, but feedback will be welcome.

[bansp]

There is a new little hook-related issue to be mentioned there, so Piotr is going to do that.

[bansp]

Except I'm halted by #487 -- should we advise the user to use an empty commit-id.xml, or maybe... fail silently when the file is not yet present, huh?

[bansp]

I'm going to leave this for (nearly) three weeks until we speak again, but one thought that may be relevant is that we should decide who precisely this doc is for: whether it's for someone who wants to serve the SIS or just contribute the recommendations and make sure that they don't push rubbish to us.

One thing to guarantee that that makes sense is simply to provide a basis for using XML-aware editing environment, with schemas that guide the creation of recommendations (on the basis of an existing template). We have that. We also have documentation of the syntax, quite extensive and up-to-date.

The nest step is for someone to (a) see their recommendations locally before they create a PR or (b) actually contribute code. I think (b) may be a very rare case (not attested yet ;-)), so let us assume that that hypothetical person would be able to navigate various obstacles and to contact us for assistance directly.

That leaves (a), and for that use case, the user doesn't care about the proper commit ID -- that is our task to provide. Ergo, they don't need to care about the hook, they just need the system working after the (somewhat tedious) setup.

So I'd suggest that we strip the guidelines maximally. Hence the first, auxiliary question: does such a user need to care about finding and using the admin password? If we could eliminate that step, things would get simpler. We need the admin user to define the rest-user, but I am now browsing the local SIS with all the permissions for the rest-user switched off -- so what do we need the rest-user for, in this setup, @margaretha ? Maybe we don't, or it could be a separate section, only for the unattested hard-core contributors? ;-)

Also (and that's a separate issue although arguably on-topic) what I'm unhappy about is the first-time access to the local instance, which produces:

Things become normal after the first random link is clicked. But this first encounter is ugly and a bit scary.