Do not submit description on custom fields

When using custom note fields on the ideas portal (and perhaps elsewhere), you can define a description to appear in the text box - presumably as a help guide to the user so they know what the field is for.  However, if a user does not enter anything in that field, that description is submitted as the custom field's value.  If the user does not override this description, the custom field should be submitted as blank rather than the value of the description.