Docs: solid-jest should be mentioned in solid home page

[zhaoyao91]

Oops, this package is so important to config solid with jest. I've struggled half day to config them until I found this pacakge. It event can't be searched by google, npm, github.

[edemaine]

I think this can be closed: it's now mentioned on https://www.solidjs.com/guides/testing

Conversely, though, perhaps the README here should link to that guide, as it provides a lot more information.