Improve Packit documentation (from non maintainers point of view)

[majamassarini]

A feedback from the First Workshop 2024 was:

My problem with Packit for a couple of weeks was: I couldn't understand
the concept in scenarios were I don't use the Packit Service in a GitHub
repo.

I don't know why it was so hard for me till I finally understood what
Packit can and can't do. I felt lost in the documentation, probably
because missing background.

After investing time to read about the different related services and
concepts. Actively getting involved in Fedora Packaging. Things became
more clear.

Even though our users are maintainers we have the feeling that new people are approaching Packit when they are still learning how to become a maintainer. For this reason we should improve our documentation from the point of view of non maintainers.

• Since the Fedora ecosystem for maintainers is quite complex, provide in our documentation an overview for it. A diagram of all the involved services and also an explanation of the more important terms.

• Link from our documentation the Fedora Maintainers Documentation resources where useful

[nforro]

I would just add, even though we have improved the documentation a lot in that regard, when you look at the front page, it's really upstream focused. For example the Who should use Packit? section doesn't mention Fedora maintainers at all, the Automating Fedora Releases section is also written from a PoV of an upstream maintainer, the big Get Started button takes you to the upstream onboarding guide...