Update spec/index.html

Co-authored-by: Andy Seaborne <andy@apache.org>

Author: Tpt

spec/index.html

@@ -4614,7 +4614,7 @@ <h2>Expressions and Testing Values</h2>
       <p>Typographical convention: XPath operators are labeled with the prefix
         <code>op:</code>. XPath operators have no namespace; <code>op:</code> is a labeling
         convention.</p>
-      <p>In SPARQL, the [[[XPATH-FUNCTIONS-31]]] [[XPATH-FUNCTIONS-31]] definitions which rely on XML and XML Schema
+      <p>In SPARQL, the [[[XPATH-FUNCTIONS-31]]] [[XPATH-FUNCTIONS-31]] definitions that rely on XML and XML Schema
         MUST use [[[XML11]]] [[XML11]] and [[[XMLSCHEMA11-2]]] [[XMLSCHEMA11-2]]</p>
       <p class="note">
         The use of XML 1.0 vs 1.1 and XML schema 1.0 vs 1.1 is