Add Go requirement to README

Signed-off-by: Christopher Crone <[email protected]>

Author: chris-crone

README.md

@@ -14,6 +14,7 @@ which uses the Docker Engine.
 ### Prerequisites
 
 * [Docker](https://docs.docker.com/install/)
+* [Go 1.13 or later](https://golang.org)
 * [compose-ref](https://github.com/compose-spec/compose-ref) in your PATH
 * Ensure that you have no running containers (see
   [issue](https://github.com/compose-spec/compatibility-test-suite/issues/5))