Documentation improvement (use-cases)

This MR introduces:

• added cloud best-practices based on https://docs.google.com/document/d/15JvsJ8q76SuH1MVIqqO7sVHWIyvVhHBTCMrMNpvzjRg discussion

related to https://gitlab.ics.muni.cz/246254/cloud-estimate-pi

@cloud @cudaadm