Document dependencies on README

[jayvdb]

Is your feature request related to a problem? Please describe.
It would be helpful if the README.md indicated which system dependencies are needed.

e.g. for openSUSE I needed https://repology.org/project/webkit2gtk3-soup2/versions , which is a bit of an odd name. For GUIX it looks like https://repology.org/project/webkitgtk-with-libsoup2/versions is the one. And Redhat & Debian are obviously hiding this under some other package name, which shouldnt be too hard to find.

Describe the solution you'd like
A list of dependencies, with repology links for each if they are spread across multiple names in the repology database, like this one is.

Ideally a bug or PR is raised in repology or elsewhere to have these odd names merged into a single entry.

Describe alternatives you've considered
Another way to assist the user would be to provide these package names in the build error, where it could be customised to the platform/distro being used, but IMO README is probably suffice for now, and is a good step towards any more informative build error message.

Would you assign yourself to implement this feature?

• Yes
• No

Additional context

[neobrain]

In case else anyone stumbles upon this: webkit2gtk3-devel is also required. Confusingly, the error message refers to version number 4.1 but that's exactly (and equally confusingly) what webkit2gtk3-devel ships.

Furthermore, xdotool-devel was required.