doc: document MANPATH as /usr/local/pgsql/share/man

The docs were advising to use /usr/local/pgsql/man instead, but that's
wrong.

Reported-By: Slawomir Sudnik
Backpatch-To: 9.1
Bug: #13894

doc/src/sgml/installation.sgml

@@ -1733,7 +1733,7 @@ set path = ( /usr/local/pgsql/bin $path )
     shell start-up file unless you installed into a location that is
     searched by default:
 <programlisting>
-MANPATH=/usr/local/pgsql/man:$MANPATH
+MANPATH=/usr/local/pgsql/share/man:$MANPATH
 export MANPATH
 </programlisting>
    </para>
@@ -2742,13 +2742,13 @@ cc-1020 cc: ERROR File = pqcomm.c, Line = 427
 
     <para>
      By default, the PostgreSQL man pages are installed into
-     <filename>/usr/local/pgsql/man</filename>.  By default, UnixWare
+     <filename>/usr/local/pgsql/share/man</filename>.  By default, UnixWare
      does not look there for man pages.  To be able to read them you
      need to modify the
      <varname>MANPATH</varname> variable
      in <filename>/etc/default/man</filename>, for example:
 <programlisting>
-MANPATH=/usr/lib/scohelp/%L/man:/usr/dt/man:/usr/man:/usr/share/man:scohelp:/usr/local/man:/usr/local/pgsql/man
+MANPATH=/usr/lib/scohelp/%L/man:/usr/dt/man:/usr/man:/usr/share/man:scohelp:/usr/local/man:/usr/local/pgsql/share/man
 </programlisting>
     </para>