DOC: removed pgpro_upgrade references from 9.5 RNs

Author: Liudmila Mantrova

doc/src/sgml/release-pro-9.5.sgml

@@ -110,7 +110,7 @@
         you must stop the <literal>postgres</literal> service.
         The script must be run on behalf of the user owning the
         database (typically postgres). Running <filename>pgpro_upgrade</filename>
-        as root will result in an error. For details, see <filename>pgpro_upgrade</filename>.
+        as root will result in an error.
       </para>
     </important>
     </para>