Update hr apps docs

I started by removing Phil from the list of with responsibility for some of our services, but then carried on through to update out of date information and add in a page related to TES.

Part of https://gitlab.developers.cam.ac.uk/uis/devops/admin/-/issues/343

Closes https://gitlab.developers.cam.ac.uk/uis/devops/hr/tes/tes-webapp/-/issues/68

Closes https://gitlab.developers.cam.ac.uk/uis/devops/hr/hr-systems/-/issues/53