[SSSD] [sssd PR#1010][comment] man: in sssd-ipa clarified trusted domains section

[justin-stephenson]

URL: https://github.com/SSSD/sssd/pull/1010
Title: #1010: man: in sssd-ipa clarified trusted domains section

justin-stephenson commented:
"""
The wording was a bit unclear in my opinion, I might suggest something like:

A trusted domain configuration can be set using the trusted domain subsection as shown in the example below. Alternatively, the `subdomain_inherit` option can be used in the parent domain._
"""

See the full comment at https://github.com/SSSD/sssd/pull/1010#issuecomment-607221673