doc: Correct row count in table

The incorrect count causes FOP to error out.

doc/src/sgml/monitoring.sgml

@@ -1279,7 +1279,7 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
          <entry>Waiting to apply WAL at recovery because it is delayed.</entry>
         </row>
         <row>
-         <entry morerows="66"><literal>IO</></entry>
+         <entry morerows="65"><literal>IO</></entry>
          <entry><literal>BufFileRead</></entry>
          <entry>Waiting for a read from a buffered file.</entry>
         </row>