--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2050,7 +2050,8 @@ include_dir 'conf.d'
          Larger values provide some cushion against spikes in demand,
          while smaller values intentionally leave writes to be done by
          server processes.
-         The default is 2.0.
+         The default is 2.0.  The value can range from <literal>2.0</literal>
+         to <literal>10.0</literal>
          This parameter can only be set in the <filename>postgresql.conf</filename>
          file or on the server command line.
         </para>