correct typo (closing quote should be U+201D)

xproc/src/main/xml/specification.xml

@@ -4412,7 +4412,7 @@ can provide some sort of default for the rest of the pipeline.</para>
     <para>Whether all steps in the XProc namespace are referred to as “standard (atomic) steps” or only the steps
     in the standard step library, depends on context and is intentionally kept fuzzy. Steps in the XProc 
     namespace that are not included in the standard step library may also be referred to as “optional standard 
-    steps“ if further distinction is required.</para>
+    steps” if further distinction is required.</para>
   <para>All of the standard (inluding optional), atomic steps are invoked in the same way:</para>
       <e:rng-pattern name="OtherAtomicStep"/>
       <para>Where “<replaceable>p:atomic-step</replaceable>” <rfc2119>must</rfc2119> be in the XProc