Added a validation for URLs on product.document to resolve an issue where incomplete links on documents will redirect to a local URL instead of an external URL. Thus leading to a page that does not exist. e.g.: youtube.com instead of https://www.youtube.com This seemed like the proper course of action as there would be no reason to not validate as any URL within the database can still be formatted properly and work the same. api.constrains does not seem to work upon creation on this model, so I opted to use the api.onchange. opw-3698591 closes odoo/odoo#155806 Signed-off-by: Ryan Cen (ryce) <ryce@odoo.com> Co-authored-by: Morgane Demesmaeker (edm) <69820391+Demesmaeker@users.noreply.github.com>