[css-text-4] Tweak markup

This is to work around speced/bikeshed#3308

Author: frivoal

css-text-4/Overview.bs

@@ -1279,9 +1279,7 @@ Expanding Between Words: the 'word-space-transform' property</h3>
 		or marked with class <code>p</code> when they also delimit a phrase.
 
 		<pre><code highlight=markup>
-		&lt;p>らいしゅう&lt;wbr>の&lt;wbr>じゅぎょう&lt;wbr>に&lt;wbr class=p
-		>たいこ&lt;wbr>と&lt;wbr>ばち&lt;wbr>を&lt;wbr class=p
-		>もって&lt;wbr>きて&lt;wbr>ください。
+		&lt;p>らいしゅう&lt;wbr>の&lt;wbr>じゅぎょう&lt;wbr>に&lt;wbr class=p>たいこ&lt;wbr>と&lt;wbr>ばち&lt;wbr>を&lt;wbr class=p>もって&lt;wbr>きて&lt;wbr>ください。
 		</code></pre>
 
 		Using this, it is possible not only to enable the rather common phrase-based spacing,