Prefixed explanation of full-range PNG

Added additional description for typical behavior.
"RGB images are typically full-range"

Author: digitaltvguy

index.html

@@ -3691,7 +3691,8 @@ <h2><span class="chunk">cICP</span> Coding-independent code points for video sig
           <p>The <code>Video Full Range Flag</code> value MUST be either <code>0</code> or <code>1</code>.</p>
 
           <aside class="note">
-            If <code>Video Full Range Flag</code> value is <code>1</code>, then the image is a <a>full-range image</a>. The vast
+            If <code>Video Full Range Flag</code> value is <code>1</code>, then the image is a <a>full-range image</a>. Typically,
+            images in the RGB color representation are stored in the full-range signal quantization, therefore the vast
             majority of computer graphics and web images, including those used in traditional PNG workflows, are <a>full-range
             images</a>. If <code>Video Full Range Flag</code> value is <code>0</code>, then the image is a <a>narrow-range
             image</a>. Narrow range images are found in video workflows where the interpretation of sample values below reference