Update index.bs

I should also preserve closing </dd>, thanks Lingqi.

Author: yoshisatoyanagisawa

docs/index.bs

@@ -500,7 +500,7 @@ spec: storage; urlPrefix: https://storage.spec.whatwg.org/
                         <dd>a new {{WindowClient}} object that represents |incumbentGlobal|'s [=relevant settings object=].</dd>
 
                         <dt>Otherwise</dt>
-                        <dd>a new {{Client}} object that represents |incumbentGlobal|'s associated worker
+                        <dd>a new {{Client}} object that represents |incumbentGlobal|'s associated worker</dd>
                     </dl>
                 1. Let |origin| be the [=serialization of an origin|serialization=] of |incumbentSettings|'s [=environment settings object/origin=].
                 1. Let |destination| be the {{ServiceWorkerGlobalScope}} object associated with |serviceWorker|.