[css-writing-modes] Fix markup error

Author: fantasai

css-writing-modes-3/Overview.bs

@@ -1583,13 +1583,13 @@ Flow-relative Directions</h3>
   <div class="example">
     <figure>
       <img src="diagrams/sizing-ltr-tb.svg">
-      <figcaption>Physical/logical terms as applicable to typical English text layout</a>
+      <figcaption>Physical/logical terms as applicable to typical English text layout</figcaption>
     </figure>
   </div>
   <div class="example">
     <figure>
       <img src="diagrams/sizing-ttb-rl.svg">
-      <figcaption>Physical/logical terms as applicable to typical Chinese text layout</a>
+      <figcaption>Physical/logical terms as applicable to typical Chinese text layout</figcaption>
     </figure>
   </div>
 

css-writing-modes-4/Overview.bs

@@ -1659,13 +1659,13 @@ Flow-relative Directions</h3>
   <div class="example">
     <figure>
       <img src="diagrams/sizing-ltr-tb.svg">
-      <figcaption>Physical/logical terms as applicable to typical English text layout</a>
+      <figcaption>Physical/logical terms as applicable to typical English text layout</figcaption>
     </figure>
   </div>
   <div class="example">
     <figure>
       <img src="diagrams/sizing-ttb-rl.svg">
-      <figcaption>Physical/logical terms as applicable to typical Chinese text layout</a>
+      <figcaption>Physical/logical terms as applicable to typical Chinese text layout</figcaption>
     </figure>
   </div>