Update UTBS page with new hosts and deployment.

This MR updates the hosts and deployment sections of the UTBS guidebook page. NOTE: not all of this exists yet, for example the hosts utbs-train1 and utbs-train2 don't appear in the list of VMs on the vcenter, I'm assuming that these will be wanted in the near future.

Closes: https://gitlab.developers.cam.ac.uk/uis/devops/utbs/utbs/-/issues/23