Fixed #13316 -- Added clarifying note about cross-database relations.
Fixed #13316 -- Added clarifying note about cross-database relations.

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extra : convert_revision : svn%3Abcc190cf-cafb-0310-a4f2-bffc1f526a37/django/trunk%4013178

Belgabor/django,Belgabor/django,Belgabor/django