[docs] Document auto __ne__ generation; provide a use case for non-trivial __ne__ (issue 4395)

[ncoghlan at gmail.com]

This looks like a good improvement to me, just one small typo.


http://bugs.python.org/review/4395/diff/13595/Doc/reference/datamodel.rst
File Doc/reference/datamodel.rst (right):

http://bugs.python.org/review/4395/diff/13595/Doc/reference/datamodel.rst#newcode1284
Doc/reference/datamodel.rst:1284: the left operand's method is has
priority.  Virtual subclassing is
s/is has/has/

http://bugs.python.org/review/4395/