[1.11.x] Refs #28192 -- Fixed documentation of ChoiceField choices requirement

Thanks Tim Graham for noticing the issue.
Backport of 54caca2d34 from master.

docs/ref/forms/fields.txt

@@ -409,7 +409,7 @@ For each field, we describe the default widget used if you don't specify
     The ``invalid_choice`` error message may contain ``%(value)s``, which will be
     replaced with the selected choice.
 
-    Takes one extra required argument:
+    Takes one extra argument:
 
     .. attribute:: choices
 
@@ -419,6 +419,7 @@ For each field, we describe the default widget used if you don't specify
         model field. See the :ref:`model field reference documentation on
         choices <field-choices>` for more details. If the argument is a
         callable, it is evaluated each time the field's form is initialized.
+        Defaults to an emtpy list.
 
 ``TypedChoiceField``
 --------------------

tests/forms_tests/field_tests/test_choicefield.py

@@ -55,6 +55,10 @@ class ChoiceFieldTest(FormFieldAssertionsMixin, SimpleTestCase):
         with self.assertRaisesMessage(ValidationError, msg):
             f.clean('6')
 
+    def test_choicefield_choices_default(self):
+        f = ChoiceField()
+        self.assertEqual(f.choices, [])
+
     def test_choicefield_callable(self):
         def choices():
             return [('J', 'John'), ('P', 'Paul')]