chore: add some hidden examples for debugging to the docs

tests/dummy/app/components/docs/queued.hbs

@@ -0,0 +1,19 @@
+<DocsDemo as |demo|>
+  <demo.example @name='queued.hbs'>
+
+    {{#if (sound-is-playing (current-sound))}}
+      <p>{{get (current-sound) 'url'}}</p>
+
+      <button type='button' {{on 'click' (stop-sound (current-sound))}}>
+        Stop
+      </button>
+    {{else}}
+      <button type='button' {{on 'click' this.playSound}}>
+        Play Queue
+      </button>
+    {{/if}}
+
+  </demo.example>
+  <demo.snippet @name='queued.hbs' />
+  <demo.snippet @name='queued.js' />
+</DocsDemo>

tests/dummy/app/components/docs/queued.js

@@ -0,0 +1,41 @@
+import Component from '@glimmer/component';
+import { inject as service } from '@ember/service';
+import { tracked } from '@glimmer/tracking';
+import { action } from '@ember/object';
+// BEGIN-SNIPPET queued.js
+export default class Queued extends Component {
+  @service stereo;
+
+  @tracked identifier;
+  @tracked queue = [];
+
+  @action
+  async playSound() {
+    this.queue = [
+      '/sounds/attention.mp3',
+      '/sounds/internet-on-computers.mp3',
+      'https://kut.streamguys1.com/kut-web.aac',
+    ];
+
+    let sound = await this.playNext();
+    sound.audioElement.setAttribute(
+      'id',
+      `id-${Math.floor(Math.random() * 10000)}`
+    );
+
+    this.stereo.on('audio-ended', ({ sound }) => {
+      console.log(sound.audioElement);
+      this.playNext();
+    });
+  }
+
+  async playNext() {
+    let next = this.queue.shift();
+    if (next) {
+      let { sound } = await this.stereo.play(next);
+
+      return sound;
+    }
+  }
+}
+// END-SNIPPET queued.js

tests/dummy/app/router.js

@@ -24,6 +24,7 @@ Router.map(function () {
     this.route('volume');
     this.route('advanced');
     this.route('testing');
+    this.route('debugging');
   });
 
   this.route('diagnostic', function () {

tests/dummy/app/templates/docs/advanced.md

@@ -1,5 +1,2 @@
 Modifiers to create position controls
 <Docs::CustomPositionControl @identifier="/sounds/works-just-like-a-vcr.mp3"/>
-
-Proxies
-<Docs::ProxyExample/>

tests/dummy/app/templates/docs/debugging.md

@@ -0,0 +1,5 @@
+Proxies
+<Docs::ProxyExample/>
+
+Queued
+<Docs::Queued/>