Editorial: add a missing double quote

Missed in 840e22f.

Author: annevk

source

@@ -118730,7 +118730,7 @@ interface <dfn>External</dfn> {
      <th> <code data-x="">accept-charset</code>
      <td> <code data-x="attr-form-accept-charset">form</code>
      <td> Character encodings to use for <span>form submission</span>
-     <td> <span>ASCII case-insensitive</span> match for "<code data-x="">UTF-8</code>
+     <td> <span>ASCII case-insensitive</span> match for "<code data-x="">UTF-8</code>"
     <tr>
      <th> <code data-x="">accesskey</code>
      <td> <span data-x="attr-accesskey">HTML elements</span>