doc: document that INFO messages always go to client.

In passing add a couple of links to the message severity table.

Backpatch because it's always been this way.

Author: Karl O. Pinc <kop@meme.com>

doc/src/sgml/config.sgml

@@ -5667,7 +5667,8 @@ local0.*    /var/log/postgresql
       </term>
       <listitem>
        <para>
-        Controls which message levels are written to the server log.
+        Controls which <link linkend="runtime-config-severity-levels">message
+        levels</link> are written to the server log.
         Valid values are <literal>DEBUG5</literal>, <literal>DEBUG4</literal>,
         <literal>DEBUG3</literal>, <literal>DEBUG2</literal>, <literal>DEBUG1</literal>,
         <literal>INFO</literal>, <literal>NOTICE</literal>, <literal>WARNING</literal>,
@@ -5693,7 +5694,9 @@ local0.*    /var/log/postgresql
         Controls which SQL statements that cause an error
         condition are recorded in the server log.  The current
         SQL statement is included in the log entry for any message of
-        the specified severity or higher.
+        the specified
+        <link linkend="runtime-config-severity-levels">severity</link>
+        or higher.
         Valid values are <literal>DEBUG5</literal>,
         <literal>DEBUG4</literal>, <literal>DEBUG3</literal>,
         <literal>DEBUG2</literal>, <literal>DEBUG1</literal>,
@@ -7025,7 +7028,9 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
       </term>
       <listitem>
        <para>
-        Controls which message levels are sent to the client.
+        Controls which
+        <link linkend="runtime-config-severity-levels">message levels</link>
+        are sent to the client.
         Valid values are <literal>DEBUG5</literal>,
         <literal>DEBUG4</literal>, <literal>DEBUG3</literal>, <literal>DEBUG2</literal>,
         <literal>DEBUG1</literal>, <literal>LOG</literal>, <literal>NOTICE</literal>,
@@ -7035,6 +7040,9 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         <literal>NOTICE</literal>.  Note that <literal>LOG</literal> has a different
         rank here than in <xref linkend="guc-log-min-messages"/>.
        </para>
+       <para>
+        <literal>INFO</literal> level messages are always sent to the client.
+       </para>
       </listitem>
      </varlistentry>