[1.4.X] Removed documentation for SMTPConnection, which was removed at r15978....

[1.4.X] Removed documentation for SMTPConnection, which was removed at r15978. Backport of r17837 from trunk.


git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.4.X@17838 bcc190cf-cafb-0310-a4f2-bffc1f526a37