[css-grid] Fix bikeshed warnings

Author: fantasai

css-grid/Overview.bs

@@ -200,13 +200,13 @@ Source-Order Independence</h3>
 	<figure class="sidefigure">
 		<img alt="Image: An arrangement suitable for portrait orientation." src="images/game-portrait.png" />
 
-		<figcaption>An arrangement suitable for ''portrait'' orientation.</figcaption>
+		<figcaption>An arrangement suitable for “portrait” orientation.</figcaption>
 	</figure>
 
 	<figure class="sidefigure">
 		<img alt="Image: An arrangement suitable for landscape orientation." src="images/game-landscape.png" />
 
-		<figcaption>An arrangement suitable for ''landscape'' orientation.</figcaption>
+		<figcaption>An arrangement suitable for “landscape“ orientation.</figcaption>
 	</figure>
 
 	Continuing the prior example,