Update cluster requirements to be consistent
To make it consistent with https://gitlab.com/gitlab-org/charts/gitlab/blob/bdb842c615dee0cbbe5c088cb491ee814d14342e/doc/installation/cloud/gke.md#creating-the-kubernetes-cluster. We state 8vCPU and 30GB of RAM is recommended.
there
Edited by Dmytro Zaporozhets (DZ)