Migration guide: Suggest $emit() as replacement for $dispatch() when used /wparent and a direct child

[LinusBorg]

This section covers the deprecation of $dispatch() and $broadcast():

https://vuejs.org/guide/migration.html#dispatch-and-broadcast-deprecated

The way it is currently worded, it makes it seem that for every instance of $dispatch(), the only solution is an event bus.

But actually, in my experience, many people use $dispatch() to communicate bewteen a parent and its direct children as well (and many often don't event know about the $emit('event') <-> @event="callback" method).

So to improve this, we should mention that in cases were $dispatch () is used between a child and its direct parent, it should be replaced with $emit() and a listener in the parent template rather than an event bus.