Fix an obvious usage nit I should have caught myself on the previous

change to this file.  Thanks, /F!

Doc/lib/xmldom.tex

@@ -162,7 +162,7 @@ This is a read-only attribute.
 \end{memberdesc}
 
 \begin{memberdesc}[Node]{attributes}
-An \class{NamedNodeList} of attribute objects.  Only elements have
+A \class{NamedNodeList} of attribute objects.  Only elements have
 actual values for this; others provide \code{None} for this attribute.
 This is a read-only attribute.
 \end{memberdesc}