Fixed #13418 -- Added notes on uniqueness requirements for natural keys. Thanks to hunajakippo for the suggestion, and Ramiro Morales for the draft text.
Fixed #13418 -- Added notes on uniqueness requirements for natural keys. Thanks to hunajakippo for the suggestion, and Ramiro Morales for the draft text.

git-svn-id: 4f9f921b081c523744c7bf24d959a0db39629563@13146 bcc190cf-cafb-0310-a4f2-bffc1f526a37

Smarsh/django,django-nonrel/django-nonrel,mitsuhiko/django,Instagram/django,Instagram/django,disqus/django-old,alex/django-old,bfirsh/django-old,sam-tsai/django-old,disqus/django-old,skevy/django,bfirsh/django-old,Smarsh/django,Instagram/django,skevy/django,jamespacileo/django-france,django-nonrel/django-nonrel,sam-tsai/django-old,jamespacileo/django-france,alex/django-old,Smarsh/django,sam-tsai/django-old,mitsuhiko/django,skevy/django,bfirsh/django-old,django-nonrel/django-nonrel,jamespacileo/django-france,sam-tsai/django-old,disqus/django-old,mitsuhiko/django,alex/django-old,Smarsh/django