Update index.html

Co-authored-by: Fuqiao Xue <xfq@w3.org>

index.html

@@ -242,7 +242,7 @@ <h3>Languages, Language Tags and Matching of Language Tags</h3>
           is a collection of one or more language ranges identifying the user's
           language preferences for use in matching. As the name suggests, such
           lists are normally ordered or weighted according to the user's
-          preferences. The HTTP [[RFC2616]] <code>Accept-Language</code>[[RFC3282]]
+          preferences. The HTTP [[RFC2616]] <code>Accept-Language</code> [[RFC3282]]
           header is an example of one kind of language priority list.</p>
         <p>A <dfn title="basic-language-range">basic language range</dfn> is
           simply a language tag used to express a language preference. An <dfn