I've noticed it's possible to set permissions and other parameters of root

I've noticed it's possible to set permissions and other parameters of root
control group, i.e. the group which is implicitly created on mount and contains
all processes.

Admin can use '.' as the group name and he/she can set group's parameters as
usual. I am not sure it's a bug or feature, I've just documented current
behavior on appropriate man page.

[Balbir, simple spell fixes]

Signed-off-by: Jan Safranek <jsafrane@redhat.com>
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
git-svn-id: https://libcg.svn.sourceforge.net/svnroot/libcg/trunk@317 4f4bb910-9a46-0410-90c8-c897d4f1cd53