Fix <sref> element too

Author: jwakely

xml/issue4118.xml

@@ -65,7 +65,7 @@ which operations "a class emulating an arithmetic type" needs to support.
 This wording is relative to <paper num="N4981"/>.
 </p>
 <ol>
-<li><p>Modify <sref ref="[meta.unary.prop]"/> as indicated:</p>
+<li><p>Modify <sref ref="[tab:time.format.spec]"/> as indicated:</p>
 
 <blockquote>
 <table style="border: 1px solid; border-spacing: 1.5em">