small typo in tutorial part 2, v1.6

[jmr.git@…]

'pub date' should be 'pub_date' in the text below:

And speaking of forms with dozens of fields, you might want to split the form up into fieldsets:

from django.contrib import admin
from polls.models import Poll

class PollAdmin(admin.ModelAdmin):
    fieldsets = [
        (None,               {'fields': ['question']}),
        ('Date information', {'fields': ['pub_date']}),
    ]

admin.site.register(Poll, PollAdmin)