docs: re-add instructions on setting wal_level for rsync use

bmomjian · bmomjian · commit 00210e3fb974 · 2017-09-20T09:36:19.000-04:00
This step was erroneously removed four days ago by me.

Reported-by: Magnus via IM

Backpatch-through: 9.5
diff --git a/doc/src/sgml/ref/pgupgrade.sgml b/doc/src/sgml/ref/pgupgrade.sgml
@@ -326,7 +326,9 @@ NET STOP postgresql-&majorversion;
      against the old primary and standby clusters.  Verify that the
      <quote>Latest checkpoint location</> values match in all clusters.
      (There will be a mismatch if old standby servers were shut down
-     before the old primary.)
+     before the old primary.)  Also, change <varname>wal_level</> to
+     <literal>replica</> in the <filename>postgresql.conf</> file on the
+     new primary cluster.
     </para>
    </step>
 
