minor #8047 Jquery datePicker syntax update (bart0356, javiereguiluz)

This PR was submitted for the 3.3 branch but it was merged into the 2.7 branch instead (closes #8047).

Discussion
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Jquery datePicker syntax update

http://api.jqueryui.com/datepicker/#option-dateFormat

Commits
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882ca41 Fixed the issue in a different way
b8c9068 Jquery datePicker syntax update

Author: xabbuh

reference/forms/types/date.rst

@@ -92,7 +92,8 @@ make the following changes::
         'attr' => ['class' => 'js-datepicker'],
     ));
 
-Assuming you're using jQuery, you can initialize the date picker via:
+Then, add the following JavaScript code in your template to initialize the date
+picker:
 
 .. code-block:: html