Expand and clarify a bit within the section on strong typing and IntelliJ IDEA support.

Ok, let's leave it with the example and as a list element but please change the text to "If you need to use content definition options like `required` and `wait` then you can still reference content elements defined using the DSL in methods on `Page` and `Module` classes as usual:", change `"..."` to some valid selector like `".async"` and rename the element name to simply `async`.