OsmoMSC: update VTY reference

This is the first update since the libosmocore changes to the 'show
online-help' generated output. Hence the produced document now benefits from
the structural improvements:
- not repeating common commands for every node;
- using section names that match the VTY prompt.

Update msc_vty_additions.xml to match the new node ID scheme.

Change-Id: I6f1698dbc205334cf69234f88b124abfce54cc9a

doc/manuals/vty/msc_vty_additions.xml

@@ -1,20 +1,17 @@
 <vtydoc xmlns='urn:osmocom:xml:libosmocore:vty:doc:1.0'>
-    <node id='32'>
-      <child_of nodeid='4' />
+    <node id='config-mncc-int'>
       <name>MNCC Internal Configuration</name>
       <description>This node allows to configure the default codecs for
       the internal call control handling.</description>
     </node>
-    <node id='35'>
-      <child_of nodeid='4' />
+    <node id='config-smpp'>
       <name>SMPP Configuration</name>
       <description>This node allows to configure the SMPP interface
 	for interfacing with external SMS applications. This section
 	contains generic/common SMPP related configuration, and no
 	per-ESME specific parameters.</description>
     </node>
-    <node id='36'>
-      <child_of nodeid='35' />
+    <node id='config-smpp-esme'>
       <name>ESME Configuration</name>
       <description>This node allows to configure one particular SMPP
       ESME, which is an External SMS Entity such as a SMS based