Adjust basic environment example to include full tutorial

Since only the "custom environment" bit is marked as "optional" in the docs.

docs/guides/building-a-basic-scene.md

@@ -305,8 +305,6 @@ To use the asset management system for an image texture:
 </a-scene>
 ```
 
-[View the example at this stage](https://aframe.io/examples/docs/basic-scene/).
-
 ## Creating a Custom Environment (Optional)
 
 Previously we had the environment component generate the environment. Though
@@ -639,4 +637,6 @@ relatively sharp and performant:
 
 And that's the basic example!
 
-[View the example](https://aframe.io/examples/docs/basic-scene-2/).
+[View the example](https://aframe.io/examples/docs/basic-scene/) (basic environment)
+
+[View the example](https://aframe.io/examples/docs/basic-scene-2/) (custom environment)

examples/docs/basic-scene/index.html

@@ -17,11 +17,31 @@
             If viewing this example locally, use http://localhost rather than http://127.0.0.1
           -->
         <img id="boxTexture" src="https://i.imgur.com/mYmmbrp.jpg">
+        <audio src="https://cdn.aframe.io/basic-guide/audio/backgroundnoise.wav" autoplay
+        preload></audio>
       </a-assets>
+
+      <a-sound src="https://cdn.aframe.io/basic-guide/audio/backgroundnoise.wav" autoplay="true"
+      position="-3 1 -4"></a-sound>
 
-      <a-box src="https://i.imgur.com/mYmmbrp.jpg" position="0 2 -5" rotation="0 45 45"
-      scale="2 2 2"></a-box>
+      <a-box
+        src="#boxTexture"
+        position="0 2 -5"
+        rotation="0 45 45"
+        scale="2 2 2"
+        animation__position="property: object3D.position.y; to: 2.2; dir: alternate; dur: 2000; loop: true"
+        animation__mouseenter="property: scale; to: 2.3 2.3 2.3; dur: 300; startEvents: mouseenter"
+        animation__mouseleave="property: scale; to: 2 2 2; dur: 300; startEvents: mouseleave"
+        animation__click="property: rotation; from: 0 45 45; to: 0 405 45; dur: 1000; startEvents: click"></a-box>
 
+      <a-entity text="value: Hello, A-Frame; color: #FAFAFA; width: 5; anchor: align"
+                position="-0.9 0.2 -3"
+                scale="1.5 1.5 1.5"></a-entity>
+
+      <a-camera>
+        <a-cursor color="#FAFAFA"></a-cursor>
+      </a-camera>
+
       <!-- Out of the box environment! -->
       <a-entity environment="preset: forest; dressingAmount: 500"></a-entity>
       <!-- Try changing the preset to one of default, contact, egypt, checkerboard, forest, goaland, yavapai, goldmine,