Enhanced driver guides

[jedevc]

This PR adds a new basic docker-container guide to match with the existing remote and kubernetes guides. Because this is a smaller and simpler driver, the guide is as well 🎉

Additionally, to improve organization, all the driver guides are moved to a dedicated folder, with an index file to describe the high of all the drivers, pulling out existing content from the README, and introducing a new feature comparison table (not sure if I'm missing any essential features?).

Also, I've added a little bit of further reading at the end of each guide to point back to the driver opts in the buildx build reference.

[crazy-max]

LGTM, PTAL @tonistiigi

[tonistiigi]

This can be follow-up but if we have guides for specific drivers I think they should cover the specific driver-opt that they take or at least link to the correct place.

[jedevc]

This can be follow-up but if we have guides for specific drivers I think they should cover the specific driver-opt that they take or at least link to the correct place.

From @crazy-max earlier:

Better use absolute url for docs reference so it doesn't break links on GitHub but I'm ok to use links to markdown files for relative file in guides folder.

Once we do a release, and all of our docs guides+references can be taken from the release branch, we can link properly :)