[1.2.X] Fixed #14403 -- Provided some extra resources on the difference...

[1.2.X] Fixed #14403 -- Provided some extra resources on the difference between FloatField and DecimalField in the model field reference. Thanks to typeshige for the report and trebor74hr and dmedvinsky for the draft patch.

Backport of [15090] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15091 bcc190cf-cafb-0310-a4f2-bffc1f526a37