Docs: Update the required build packages for fedora based systems.

Description

I was following the installation docs 1.1.3+176.g9defbb6 and noticed there was a build dependency missing, at least for Fedora 28 haven't tried the others.

When trying to build ruamel.yaml it would error and complain about Python.h missing.

I am not sure how this was not caught by the Fedora 27 CI job. I suspect that something previously might have been pulling python3-devel as a dependency and that was later dropped when the packages were upgraded in Fedroa 28. Although I haven't investigated further.

Changes proposed in this merge request:

• Added python3-devel as build requirement in the fedora installation docs.

This merge request, when approved, will close issue/bug:

---

Thanks for the patch @alatiera; we have been recommending installing psutil python package from the distro package manager to avoid the dependency on python-devel; maybe we should do the same for ruamel.yaml as well?

@tristanvb @juergbi what do you think?

added Documentation label

Thanks @alatiera ! merged at 96d07153 with some additional fixes

closed