[SSSD] [sssd PR#8] MAN: Document the ldap_user_gid_number option (comment)

[fidencio]

jhrozek commented on a pull request

"""
* master: 6f59bb822d1e54e178207be45e382f4ee173c434
"""

See the full comment at https://github.com/SSSD/sssd/pull/8#issuecomment-244054299