Fix JS components console error "Error: <Component> is transitioning"

docs/_includes/callout-danger-async-methods.md

@@ -0,0 +1,7 @@
+{% callout danger %}
+#### Asynchronous methods and transitions
+
+All API methods are **asynchronous** and start a **transition**. They returns to the caller as soon as the transition is started but **before it ends**. In addition, a method call on a **transitioning component will be ignored**.
+
+[See our Javascript documentation for more informations.]({{ site.baseurl }}/getting-started/javascript/#content)
+{% endcallout %}