Adds entries for context and instanceID

app/docs/md/elements/state/index.md

@@ -38,10 +38,12 @@ export default function MyElement ({ html, state }) {
 
 </doc-code>
 
-The state object contains two top level entries:
+The state object contains four top level entries:
 
 - `attrs`, which contains all the key value pairs of attributes passed into your custom element’s instance
 - `store`, which contains the global state of your Enhance application
+- `instanceID`, which is a unique ID per instance of Custom Element
+- `context`, which is an Object that can be used to pass state to child elements to avoid prop drilling.
 
 These two different entries allow you to work with both basic and complex state in powerful ways without the need for complex abstractions or third party libraries.