Remove docker-compose example

It got out of sync after:
gitlab-org/gitlab/commit/c075e721a7f6a927e02496f737479c6360c8e6c8

Co-authored-by: Achilleas Pipinellis <axil@gitlab.com>

docker/README.md

@@ -1 +1 @@
-The latest docker guide can be found here: [GitLab Docker images](/doc/docker/README.md).
+The latest Docker guide can be found here: [GitLab Docker images](https://docs.gitlab.com/ee/install/docker.html).

docker/docker-compose.yml

@@ -1,15 +0,0 @@
-web:
-  image: 'gitlab/gitlab-ce:latest'
-  restart: always
-  hostname: 'gitlab.example.com'
-  environment:
-    GITLAB_OMNIBUS_CONFIG: |
-      external_url 'https://gitlab.example.com'
-  ports:
-    - '80:80'
-    - '443:443'
-    - '22:22'
-  volumes:
-    - '/srv/gitlab/config:/etc/gitlab'
-    - '/srv/gitlab/logs:/var/log/gitlab'
-    - '/srv/gitlab/data:/var/opt/gitlab'