Pop up message when Customers/Employees select Modifier Groups

When a customer/employee clicks into a modifier group it would be very beneficial to allow the option for a pop up window to give a message informing them of information we want to include about that item.

Example. If a customer clicks "Hot"(Modifier) as the Temperature(Modifier Group) then a Pop up window will appear informing them that Add-Ons cannot be added if they choose this option. This can be repurposed into different things with a customizable message, such as "Contains nuts, Milk, etc". 

We would be able to choose to place these messages at the Modifier, Modifier group, and Product/items level. We should also allow the option to disable in the store via POS Settings, since the messages will not be necessary for some employees.