fix: Sets domain name lower case in realmd.conf section header

[chuckmilam]

Enhancement: Set domain name lower case in realmd.conf section header

Reason: Realm specific sections should always contain the domain name in lower case as their section header.

[justin-stephenson]

Ack, thank you for the fix.

[spetrosi]

[citest]

[spetrosi]

I updated PR summary. Posting the initial summary for history:

It appears the variable "ad_integration_computer_ou" does not do what I would expect it to do.

Per the README, it is:

"The distinguished name of an organizational unit to create the computer account."

As I painfully discovered over several days, setting this variable with an appropriate OU results in no change, and computers are joined to the domain in the default OU.

I looked through the code, and sure enough, "ad_integration_computer_ou" is only mentioned in the "realmd.conf.j2" file.

I've modified "tasks/main.yml" to correctly add the "--computer-ou" option to the "realm join" command, but before I jump through what appears to be pages of hoops setting up a Fedora VM and "tox-lsr" and whatnot, I figured I'd ask here to make sure I'm on the right track in believing the "ad_integration_computer_ou" variable should do more than just update a value in "sssd.conf."