restore a deleted empty line.

Author: Guohui Deng

fetch.bs

@@ -3798,6 +3798,7 @@ from a <a for=/>header list</a> <var>headers</var>, run these steps:
 </ol>
 </div>
 
+
 <h3 id=content-type-header>`<code>Content-Type</code>` header</h3>
 
 <p>The `<code>Content-Type</code>` header is largely defined in HTTP. Its processing model is