samba-tool: Update 'samba-tool gpo list <>' description
We have a command to get gpo listing from Active Directory. samba-tool gpo list
This command can list GPOs for both username and machinename, But command help only shows 'username'.
This PR
- Updates the option presented in help.
- Updates name of variable used to retrieve GPO so that it's not misleading if someone reads code later on
Fixes: https://bugzilla.samba.org/show_bug.cgi?id=14016
Signed-off-by: Amit Kumar amitkuma@redhat.com