Update suse.md
Update suse.md

In the **Install using the repository** section, the GPG implied location was identified as `<DOCKER-EE-URL>/sles/12.3/<ARCHITECTURE>/stable-<VERSION>/sles/gpg` which does not exist. The correct location is `<DOCKER-EE-URL>/sles/gpg`. I introduce a second variable here called `DOCKER_EE_BASE_URL` which will be used to distinguish between the root level of the directory and aid in correctly locating the gpg key for the `rpm --import` command.
londoncalling/docker.github.io,docker/docker.github.io,docker/docker.github.io,londoncalling/docker.github.io,londoncalling/docker.github.io,thaJeztah/docker.github.io,thaJeztah/docker.github.io,londoncalling/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io,docker/docker.github.io,londoncalling/docker.github.io,thaJeztah/docker.github.io,thaJeztah/docker.github.io,docker/docker.github.io