Fixed typo in Group module docstring.
Fixed typo in Group module docstring.

artscoop/django-admin-tools,artscoop/django-admin-tools,glic3rinu/django-admin-tools,glic3rinu/django-admin-tools,glic3rinu/django-admin-tools,glic3rinu/django-admin-tools,artscoop/django-admin-tools,artscoop/django-admin-tools