[css-writing-modes] Fix typo

Author: kojiishi

css-writing-modes/Overview.bs

@@ -801,13 +801,13 @@ Block Flow Direction: the 'writing-mode' property</h3>
   <dl dfn-for=writing-mode dfn-type=value>
     <dt><dfn>horizontal-tb</dfn></dt>
     <dd>Top-to-bottom <i>block flow direction</i>.
-        Both the <i>writing mode</i> and <i>typographic mode</a> are horizontal.</dd>
+        Both the <i>writing mode</i> and <i>typographic mode</i> are horizontal.</dd>
     <dt><dfn>vertical-rl</dfn></dt>
     <dd>Right-to-left <i>block flow direction</i>.
-        Both the <i>writing mode</i> and <i>typographic mode</a> are vertical.</dd>
+        Both the <i>writing mode</i> and <i>typographic mode</i> are vertical.</dd>
     <dt><dfn>vertical-lr</dfn></dt>
     <dd>Left-to-right <i>block flow direction</i>.
-        Both the <i>writing mode</i> and <i>typographic mode</a> are vertical.</dd>
+        Both the <i>writing mode</i> and <i>typographic mode</i> are vertical.</dd>
   </dl>
 
   <p>The 'writing-mode' property specifies the <i>block flow direction</i>,