* 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
`acme-dns` supports binding the API to a specific interface instead of
all interfaces by providing an `ip` address in the `[api]` configuration
section. Prior to this commit the `ip` field wasn't shown in the example
configuration in the README. This commit adds an example showing how to
configure `acme-dns` to listen only on `127.0.0.1` to the example config
and describes what the default value (`""`) does.
This commit fixes the JSON examples in the README. There was a missing
`]` in the example input, a missing IP range in the reflected output,
and a few trailing `,` that shouldn't have been there.