refactor ee-docs landing page
What does this MR do?
Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/2240
Reorganize EE-docs landing page. Follows https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10754
Screenshot:
Current version:
cc/ @axil @seanpackham
Edited by 🤖 GitLab Bot 🤖