docs: add Vue 3 video lessons (#490)

Co-authored-by: Ben Hong <ben@bencodezen.io>

Author: rahaug

src/guide/component-custom-events.md

@@ -23,6 +23,8 @@ For these reasons, we recommend you **always use kebab-case for event names**.
 
 ## Defining Custom Events
 
+<div class="vueschool"><a href="https://vueschool.io/lessons/defining-custom-events-emits?friend=vuejs" target="_blank" rel="sponsored noopener" title="Learn how to define which events a component can emit with Vue School">Learn how to define emitted events with a free lesson on Vue School</a></div>
+
 Emitted events can be defined on the component via the `emits` option.
 
 ```js

src/guide/teleport.md

@@ -1,6 +1,6 @@
 # Teleport
 
-[Watch a free video about Teleport on Vue Mastery](https://www.vuemastery.com/courses/vue-3-essentials/teleport)
+<div class="vueschool"><a href="https://vueschool.io/lessons/vue-3-teleport?friend=vuejs" target="_blank" rel="sponsored noopener" title="Learn how to use teleport with Vue School">Learn how to use teleport with a free lesson on Vue School</a></div>
 
 Vue encourages us to build our UIs by encapsulating UI and related behavior into components. We can nest them inside one another to build a tree that makes up an application UI.