Update docs for v1.0.0 beta
Closes https://gitlab.com/gitlab-org/quality/gitlab-environment-toolkit/-/issues/10 https://gitlab.com/gitlab-org/quality/gitlab-environment-toolkit/-/issues/22
MR brings in the first draft of new rewritten docs for the Toolkit. Focuses on GCP first with Azure and AWS steps coming in subsequent MRs.
Edited by Grant Young