Feature request: quickly enable/disable some docsets

[romgrk]

Usually when working on a project, I'll have 1-2 docsets in use. It's annoying that it will search for entries in all docsets while I don't use them. It would be great if we could say, "I'm working with this, this, and this docset, please ignore the rest for the moment".

[jkozera]

Would the 'user-defined docset groups' feature help?

See https://github.com/jkozera/zevdocs/releases/tag/0.5.0 for a demo.