Properly document cosmos.py functions

from https://code.greenhost.net/openappstack/bootstrap/merge_requests/15#note_43814:

def create_domain_record(domain: str, name: str, data: str,  Arie Peterson @arie commented just now: 

Some more documentation on what these parameters mean, and how they should be formatted, would be really useful for future use. At Greenhost we strive to put that in the docstring, and use this format to enable automatic documentation formatting using sphinx.