Installation page visuals

https://getkong.org/install/ is a nice installation page

can we add more icons to https://about.gitlab.com/installation/ ?

I think we just need icons for Omnibus package installation, Update, and Other official installation methods. The other methods are not recommended.

Maybe we also need official workmarks for GitLab CE and GitLab EE, we can reuse them for example on https://docs.gitlab.com/

/cc @lukebabb

**Iteration 1:**