fixes gradient function typo from linear-gradient to radial

Author: Adam Argyle

css-images-4/Overview.bs

@@ -1355,9 +1355,9 @@ to customize color interpolation in gradients as described in [[css-color-4#inte
 	which here gives almost the same result as CIE Lab.
 
 	<ul class="lang-css">
-		<li><code>linear-gradient(in lab farthest-side at left bottom, color(display-p3 0.918 0.2 0.161), #081)</code></li>
-		<li><code>linear-gradient(in srgb farthest-side at left bottom, color(display-p3 0.918 0.2 0.161), #081)</code></li>
-		<li><code>linear-gradient(in oklab farthest-side at left bottom, color(display-p3 0.918 0.2 0.161), #081)</code></li>
+		<li><code>radial-gradient(in lab farthest-side at left bottom, color(display-p3 0.918 0.2 0.161), #081)</code></li>
+		<li><code>radial-gradient(in srgb farthest-side at left bottom, color(display-p3 0.918 0.2 0.161), #081)</code></li>
+		<li><code>radial-gradient(in oklab farthest-side at left bottom, color(display-p3 0.918 0.2 0.161), #081)</code></li>
 	</ul>
 
 	<!-- source: images/radial-rectangular-f01-081.html -->