Doc: Document pg_stat_recovery_prefetch.stats_reset.

This column was missing from the table that describes the new view.

Author: Shinoda, Noriyoshi (PN Japan FSIP) <noriyoshi.shinoda@hpe.com>
Discussion: https://postgr.es/m/DM4PR84MB173401C19A0EB9B1CAAB197CEED29@DM4PR84MB1734.NAMPRD84.PROD.OUTLOOK.COM

doc/src/sgml/monitoring.sgml

@@ -3009,6 +3009,17 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
     </thead>
 
     <tbody>
+     <row>
+      <entry role="catalog_table_entry">
+       <para role="column_definition">
+        <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+       </para>
+       <para>
+        Time at which these statistics were last reset
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry">
        <para role="column_definition">