Add description of temporary column into pg_replication_slots doc.

Ayumi Ishii

doc/src/sgml/catalogs.sgml

@@ -9315,6 +9315,15 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
       null. Only logical slots have an associated database.</entry>
      </row>
 
+     <row>
+      <entry><structfield>temporary</structfield></entry>
+      <entry><type>boolean</type></entry>
+      <entry></entry>
+      <entry>True if this is temporary replication slot. Temporary slots are
+      not saved to disk and are automatically dropped on error or when
+      the session has finished.</entry>
+     </row>
+
      <row>
       <entry><structfield>active</structfield></entry>
       <entry><type>boolean</type></entry>