[2.2.x] Fixed #30505 -- Doc'd how changes in the order of Field.choices affect migrations.

Backport of 5248abe9b0 from master

AUTHORS

@@ -148,6 +148,7 @@ answer newbie questions, and generally made Django that much better:
     bthomas
     btoll@bestweb.net
     C8E
+    Caio Ariede <caio.ariede@gmail.com>
     Calvin Spealman <ironfroggy@gmail.com>
     Cameron Curry
     Cameron Knight (ckknight)

docs/ref/models/fields.txt

@@ -80,7 +80,7 @@ If a field has ``blank=False``, the field will be required.
 
 .. attribute:: Field.choices
 
-An :term:`iterable` consisting itself of iterables of exactly two items (e.g.
+A :term:`sequence` consisting itself of iterables of exactly two items (e.g.
 ``[(A, B), (A, B) ...]``) to use as choices for this field. If choices are
 given, they're enforced by :ref:`model validation <validating-objects>` and the
 default form widget will be a select box with these choices instead of the
@@ -155,11 +155,14 @@ method to retrieve the human-readable name for the field's current value. See
 :meth:`~django.db.models.Model.get_FOO_display` in the database API
 documentation.
 
-Note that choices can be any iterable object -- not necessarily a list or tuple.
-This lets you construct choices dynamically. But if you find yourself hacking
-:attr:`~Field.choices` to be dynamic, you're probably better off using a proper
-database table with a :class:`ForeignKey`. :attr:`~Field.choices` is meant for
-static data that doesn't change much, if ever.
+Note that choices can be any sequence object -- not necessarily a list or
+tuple. This lets you construct choices dynamically. But if you find yourself
+hacking :attr:`~Field.choices` to be dynamic, you're probably better off using
+a proper database table with a :class:`ForeignKey`. :attr:`~Field.choices` is
+meant for static data that doesn't change much, if ever.
+
+.. note::
+    A new migration is created each time the order of ``choices`` changes.
 
 Unless :attr:`blank=False<Field.blank>` is set on the field along with a
 :attr:`~Field.default` then a label containing ``"---------"`` will be rendered

docs/topics/db/models.txt

@@ -154,7 +154,7 @@ ones:
     <Field.blank>`, the field will be required.
 
 :attr:`~Field.choices`
-    An :term:`iterable` of 2-tuples to use as choices for this field. If this
+    A :term:`sequence` of 2-tuples to use as choices for this field. If this
     is given, the default form widget will be a select box instead of the
     standard text field and will limit choices to the choices given.
 
@@ -168,6 +168,9 @@ ones:
             ('GR', 'Graduate'),
         ]
 
+    .. note::
+        A new migration is created each time the order of ``choices`` changes.
+
     The first element in each tuple is the value that will be stored in the
     database. The second element is displayed by the field's form widget.