Refactor the requirements docs in regards to the reference architectures
Problem to solve
In !30781 (merged) we're adding a single page for the reference architectures which lists the various components.
In https://docs.gitlab.com/ee/install/requirements.html we also list the minimum requirements in order to install GitLab, and make a minor mention of the number of users in the CPU and RAM sections.
If I were I user, I'd be confused which to follow and when.
Proposal
We should refactor the requirements page and point to the new reference architectures page more prominently.