Apply suggestions from code review

Co-authored-by: Andy Seaborne <[email protected]>

Author: gkellogg

spec/index.html

@@ -961,8 +961,8 @@ <h3>Literals</h3>
         to a <a>literal value</a>.</li>
       <li>If and only if the <a>datatype IRI</a> is
         <code>http://www.w3.org/1999/02/22-rdf-syntax-ns#langString</code> or
-        <code>http://www.w3.org/1999/02/22-rdf-syntax-ns#dirLangString</code>, a
-        non-empty <dfn class="export">language tag</dfn> as defined by [[!BCP47]]
+        <code>http://www.w3.org/1999/02/22-rdf-syntax-ns#dirLangString</code>, there is a
+        non-empty <dfn class="export">language tag</dfn> as defined by [[!BCP47]].
         The language tag MUST be well-formed according to
         <a data-cite="bcp47#section-2.2.9">section 2.2.9</a>
         of [[!BCP47]],