Add id to example component

Author: FrenchDilettante

addon/components/docs-demo/x-example/component.js

@@ -4,5 +4,10 @@ import layout from './template';
 export default Component.extend({
   layout,
 
-  classNames: 'docs-demo-example'
+  classNames: 'docs-demo-example',
+
+  didReceiveAttrs() {
+    this._super(...arguments);
+    this.set('elementId', 'example-' + this.get('name'));
+  }
 });