doc: Fix link reference for PGSSLMAXPROTOCOLVERSION

The link was pointing to the minimum protocol version.  Incorrect as of
ff8ca5fa.

Author: Daniel Gustafsson
Discussion: https://postgr.es/m/F893F184-C645-4C21-A2BA-583441B7288F@yesql.se
Backpatch-through: 13

doc/src/sgml/libpq.sgml

@@ -7872,7 +7872,7 @@ myEventProc(PGEventId evtId, void *evtInfo, void *passThrough)
        <primary><envar>PGSSLMAXPROTOCOLVERSION</envar></primary>
       </indexterm>
       <envar>PGSSLMAXPROTOCOLVERSION</envar> behaves the same as the <xref
-      linkend="libpq-connect-ssl-min-protocol-version"/> connection parameter.
+      linkend="libpq-connect-ssl-max-protocol-version"/> connection parameter.
      </para>
     </listitem>