Remove outdated ForeignKey manager documentation

It appears the documentation here on accessing a related manager directly from a class is out of date. When I set up my models.py the same as in the example here, I get:

    In [1]: from myapp.models import *

    In [2]: Blog.entry_set
    Out[2]: <django.db.models.fields.related.ForeignRelatedObjectsDescriptor at 0x108923a50>

This is what I'd expect from my reading of django.db.models.fields.related.