Revisit documentation on supported OS versions and packages

[aaronkaplan]

https://github.com/certtools/intelmq/pull/2407/files has an interesting discussion on OS versions , what we officially support and what not. What would work (with maybe some tweaks or newer packages) but is not recommended anymore etc.

I suggest we document this in our new super cool docs.intelmq.org documenation (thx again @gethvi )!
But this can come after 3.2.2 if needed.

This issue is here so that we don't forget.

[gethvi]

I think it's completely fine to remove OS support if they don't meet our dependencies in the necessary version. After all this only concerns native deb/rpm packages. Installation via pip will often work just fine anyway. I am aware that some organizations don't allow installation via pip, but frankly that's their problem.

We could keep two lists:

• "fully supported" OSs. Something like what @kamil-certat suggested with "Recommended setup". We provide latest native packages for fully supported OSs. All dependencies are met.

• "partially supported" OSs. This is for:

  • formerly fully supported OSs (with native package only available up to some non-latest version)
  • OSs usable with pip installation (and without actively maintained installation instructions)
  • OSs that have unmet dependencies for some bots (not core libs)

[sebix]

We had the split of recommended and "only" supported systems in the past, but then both lists shrunk so much that we ended up with just one. For example, we had packages for Fedora, which was not a recommended platform, because of missing tests, but it was supported and worked much better than e.g. CentOS because Fedora had many optional Python libraries and up-to-date Python versions.
Now, as the interest in IntelMQ is stagnating, I suggest keeping the list of supported versions as small as possible and only focusing on very few options that are reasonable to maintain with little effort.