Add a description of additional e-mail triggers, written with a store manager in mind.

In the "Email triggers" article, mention new triggers, add them to the list of use cases, too.

• Price Drop Trigger is sent when a price of a product that a user previously visited becomes lower (not only when a base price drops, but when a certain flag or attribute applies)
• Post Visit Retargeting Trigger is similar to reactivation trigger but is based on "also-clicked" model modified by user context. It's goal is to suggest items similar to the ones that the user has viewed but not purchased.

In "Events" article, describe the WISHLIST and REMOVE_FROM_WISHLIST event.