quine: add package quine dmitri.shuralyov.com/scratch#2

s/main/quine/ to match the path of the command being added.

I suggest either adding a quine that can be licensed via the existing BSD-3-Clause LICENSE at the top level of the repo (see the "License" link at https://dmitri.shuralyov.com/scratch), or if you'd really rather stick with this command having a different license, then move it into a file named LICENSE in this directory. That way it will be recognized by this code host.

At that point the README.md is fairly empty. You can move its content to a package comment in quine.go doc.go, so that it too would be recognized and displayed at the future package page. Edit: I realize now that adding it to quine.go would interfere with its functionality hehe.