Fixed #10415 -- Added documentation for features added in r7627 and r7630; extensibility points for the ModelAdmin and AdminSite. Thanks to Ramiro Morales for the draft text.
Fixed #10415 -- Added documentation for features added in r7627 and r7630; extensibility points for the ModelAdmin and AdminSite. Thanks to Ramiro Morales for the draft text.

git-svn-id: 4f9f921b081c523744c7bf24d959a0db39629563@11095 bcc190cf-cafb-0310-a4f2-bffc1f526a37

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