Improved docs/authentication.txt to note that messages only work with registered users, not anonymous users
Improved docs/authentication.txt to note that messages only work with registered users, not anonymous users

git-svn-id: 4f9f921b081c523744c7bf24d959a0db39629563@1142 bcc190cf-cafb-0310-a4f2-bffc1f526a37

disqus/django-old,Smarsh/django,django-nonrel/django-nonrel,Smarsh/django,jamespacileo/django-france,bfirsh/django-old,hugs/django,t11e/django,sam-tsai/django-old,alex/django-old,jamespacileo/django-france,dcramer/django-compositepks,skevy/django,rawwell/django,dcramer/django-compositepks,alex/django-old,django-nonrel/django-nonrel,mitsuhiko/django,t11e/django,hugs/django,Smarsh/django,dcramer/django-compositepks,bfirsh/django-old,hugs/django,django-nonrel/django-nonrel,mitsuhiko/django,jamespacileo/django-france,rawwell/django,Instagram/django,sam-tsai/django-old,disqus/django-old,Instagram/django,sam-tsai/django-old,disqus/django-old,bfirsh/django-old,Smarsh/django,mitsuhiko/django,alex/django-old,skevy/django,Instagram/django,skevy/django,rawwell/django,t11e/django,sam-tsai/django-old