[doc] Advanced documentation / add wiki section

[adlerweb]

At the moment most documentation is in README.md. While this is sufficient for most basic stuff it took quite some time to understand how the tools used work together, especially when dealing with GPG or custom repositories. I couldn't really find any advanced documentation for either aurto or aurutils and while the aurto repo would be the place I would look for this first I'm not sure the readme is a good place for this rather specific stuff. Any ideas on how to make this knowledge accessible or easier to find for other aurto users? Maybe enable the wiki section?

Things I have on my notebook:

• Importing GPG-keys, for example to allow signed packages to be verified
  aurto uses a dedicated user for most operations. Keys must be added to the keyring of this user, for example:
  sudo -u aurto gpg --search 0x123456789abcdef
• Adding a key to the pacman keystore
  aurto uses aurutils/aurbuild to build packages. Since their chroot is synced, keys added there will also be available during aurto builds. For example:
  arch-chroot /var/lib/aurbuild/x86_64/root pacman-key -r 0x123456789abcdef
• Adding an repository
  Additional repositorys may be specified in /etc/aurto/pacman-chroot.conf.
  (granted, thats somewhat already in readme...)

[alexheretic]

I wouldn't be against a wiki for aurto if that's helpful to people, I've enabled it: https://github.com/alexheretic/aurto/wiki

However, I think the real complexity lies with upstream aurutils & the arch core components, rather than aurto itself. I've tried to keep the scope of this project limited. Generally I'd advise people to use aurutils directly if their requirements outstrip aurto.

aurto uses a dedicated user for most operations

Not exactly right, whichever user that calls aurto init is used to do all non-root tasks. It doesn't have a dedicated user called "aurto" (unless that's been explicitly setup).