README: simplify installation instructions with `go get`. (#41)
README: simplify installation instructions with `go get`. (#41)

* README: simplify installation instructions with `go get`.

Prior to this commit the installation instructions in the README had you
use `git clone` and then `go build`. This can be collapsed into one step
using a more idiomatic `go get` command. This commit updates the README
accordingly.

* Also mention supported config file locations

* Fix go get URL

joohoi/acme-dns,joohoi/acme-dns