Update the aws page

Our AWS page needs some ❤ https://about.gitlab.com/aws/

As an AWS noob, I struggled a bit to understand it while working on https://gitlab.com/gitlab-org/gitlab-ce/issues/29199.

Two options:

1. Update it and make it pretty
2. Move it under our official docs https://docs.gitlab.com/ce/install/

Personally, I think option 2 is better. @regisF thoughts?