Fixed #20986 -- Enabled SelectDateWidget to use custom months

Reviewed by Trac alias MarkusH.

docs/releases/1.7.txt

@@ -213,6 +213,10 @@ Forms
   return ``self.cleaned_data``. If it does return a changed dictionary then
   that will still be used.
 
+* :attr:`SelectDateWidget.months
+  <django.forms.extras.widgets.SelectDateWidget.months>` can be used to
+  customize the wording of the months displayed in the select widget.
+
 Management Commands
 ^^^^^^^^^^^^^^^^^^^