doc: minor updates to "repmgr standby clone" reference

- remove references to repmgr 4.0.4 (present because feature
  was added in a minor release, but that's a long time ago)
- note configuration is appended to postgresql.auto.conf

doc/repmgr-standby-clone.xml

@@ -226,8 +226,8 @@
    <para>
      Then execute the command <command>repmgr standby clone --recovery-conf-only</command>.
      This will create the <filename>recovery.conf</filename> file needed to attach
-     the node to its upstream (in PostgreSQL 12 and later: write replication configuration
+     the node to its upstream (in PostgreSQL 12 and later: append replication configuration
-	 to <filename>postgresql.auto.conf</filename>), and will also create a replication slot on the
+     to <filename>postgresql.auto.conf</filename>), and will also create a replication slot on the
      upstream node if required.
    </para>
    <para>
@@ -242,12 +242,6 @@
 	 making any changes.
    </para>
 
-   <note>
-     <para>
-       <option>--recovery-conf-only</option> was introduced in &repmgr; <link linkend="release-4.0.4">4.0.4</link>.
-     </para>
-   </note>
-
   </refsect1>
 
   <refsect1>
@@ -321,7 +315,7 @@
         <term><option> --recovery-conf-only</option></term>
         <listitem>
           <para>
-            Create recovery configuration for a previously cloned instance. &repmgr; 4.0.4 and later.
+            Create recovery configuration for a previously cloned instance.
           </para>
 		  <para>
 			In PostgreSQL 11 and earlier, the replication configuration will be