[css-fonts-4] Add palette example

Author: svgeesus

css-fonts-4/Overview.bs

@@ -5672,7 +5672,27 @@ User-defined font color palettes: The ''@font-palette-values'' rule</h3>
         }
     </pre>
 
-    The ''@font-palette-values'' rule accepts the descriptors defined in this specification.
+	The ''@font-palette-values'' rule accepts the descriptors defined in this specification.
+
+	<div class="example">
+		Modify Bixa Color's color palette.
+
+        <pre>
+        @font-palette-values Cooler {
+            font-family: Bixa;
+            base-palette: 1;
+            override-color:
+                1 #7EB7E4;
+        }
+		</pre>
+
+		<figure>
+			<img src="images/bixa-colors.png" alt="overriding a color"/>
+			<figcaption>Bixa Color by Novo Typo. Above, using the colors in the font;
+				below, the orange changed to a blue.</figcaption>
+		</figure>
+
+    </div>
 
     <div class="example">
         Modify Handover Sans's color palette