Link unlisten.sgml into what I hope are the right places.

tglsfdc · tglsfdc · commit ad567f07bed0 · 1998-10-08T00:19:49.000Z
diff --git a/doc/src/sgml/ref/allfiles.sgml b/doc/src/sgml/ref/allfiles.sgml
@@ -106,6 +106,7 @@
 <!entity select             system "select.sgml">
 <!entity set                system "set.sgml">
 <!entity show               system "show.sgml">
+<!entity unlisten           system "unlisten.sgml">
 <!entity update             system "update.sgml">
 <!entity vacuum             system "vacuum.sgml">
 
diff --git a/doc/src/sgml/ref/commands.sgml b/doc/src/sgml/ref/commands.sgml
@@ -57,6 +57,7 @@ commands supported by <productname>Postgres</productname>.
 &select;
 &set;
 &show;
+&unlisten;
 &update;
 &vacuum;
 
