List displays + resolutions

[schrottkatze]

I thought it might be useful to be able to list connected monitors, their resolutions (and refresh rates, maybe?) and how to address them in layaway. Or document how one could get that info.

For example, just now it took me quite a bit of guesswork to figure out the external monitor i'm using is hdmi2 and not just hdmi

[MultisampledNight]

Thanks! Yeah, I agree.

For reference, the current workflow is:

1. Scrolling in the readme to the section Usage details
2. Clicking on the parse::dsl link
3. Puzzling together from the listed ABNF and from the info module what the specifier is

This is suboptimal. I think this could be improved by:

• As you mentioned, being able to list connected displays and their configurations at runtime.
• Adding a more in-yer-face tutorial link directly at the top of the readme.

I do think they're sensible, I don't think I can do them anytime soon though. Maybe someone else can, or I just get back to this in a few months.