Title: #604: MAN: Document the re_expression needed to suport @-signs in the groupnames
In the 2.0 release we will be able to change the default regular expression
that will allow to consume @-signs in the name, but since the 1.x branches
need to stay backwards compatible, let's only document the regex for now.
According to comments in https://bugzilla.redhat.com/show_bug.cgi?id=1383520
the modified regular expression already helped some users, but not all.
So, more work and investigation is needed (for example it is not clear to me
whether the issue in parsing is in the extdom plugin or on the sssd side),
but we can document the changed default already.
To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/604/head:pr604
git checkout pr604