Update workflow documentation
We document our GitLab flow at https://guidebook.devops.uis.cam.ac.uk/en/latest/workflow/gitlab/ and https://guidebook.devops.uis.cam.ac.uk/en/latest/workflow/flows/ change the GitLab workflow documentation to be focussed more on how a product team as a whole can use GitLab. This is based on a draft "cheat sheet" used for the SMI project members.
Take the opportunity to remove the HTTPS->HTTP redirect hack as noted in #35 (closed).