1475043-Allow-commands.update()-to-un-set-a-shortcut (#5696)
1475043-Allow-commands.update()-to-un-set-a-shortcut (#5696)

Adding the `details` properties to `update` to enable a note to be added to `shortcut` about the ability to set it to a empty string in Firefox 74 and after to clear a shortcut assignment.
mdn/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data