Fix spelling error

Author: mirisuzanne

css-cascade-5/Overview.bs

@@ -1050,13 +1050,13 @@ Cascade Layers</h3>
 
 	<pre class='lang-css'>
 	audio {
-		/* speceficity of 0,0,1 - implicit (final) layer */
+		/* specificity of 0,0,1 - implicit (final) layer */
 		display: flex;
 	}
 
 	@layer defaults {
 		audio[controls] {
-			/* speceficity of 0,1,1 - explicit "defaults" layer */
+			/* specificity of 0,1,1 - explicit "defaults" layer */
 			display: block;
 		}
 	}