[IMP] pos_discount: better tooltips
[IMP] pos_discount: better tooltips

Closes #9944

ygol/odoo,ygol/odoo,ygol/odoo,hip-odoo/odoo,dfang/odoo,hip-odoo/odoo,ygol/odoo,dfang/odoo,ygol/odoo,dfang/odoo,ygol/odoo,hip-odoo/odoo,hip-odoo/odoo,dfang/odoo,hip-odoo/odoo,dfang/odoo,ygol/odoo,hip-odoo/odoo,dfang/odoo