Document dependencies on README

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

Review README.md and identify the system dependencies needed to build or use the project, starting with the WebKitGTK dependency mentioned in the issue. Check the relevant Repology links and add a concise dependency list with platform or distribution-specific package names where they differ; done means the README makes these requirements clear.