doc: add OsmoGbProxy VTY reference

Depends: (osmo-gsm-manuals) I4dea3e07b88175b2a88e577129360af7ec5f87e1
Related: OS#4292
Change-Id: I24c3ca2fc2446673edceefb797c7d800c3a1a5d2
diff --git a/doc/manuals/vty-osmogbproxy/gbproxy_vty_additions.xml b/doc/manuals/vty-osmogbproxy/gbproxy_vty_additions.xml
new file mode 100644
index 0000000..6da2d2f
--- /dev/null
+++ b/doc/manuals/vty-osmogbproxy/gbproxy_vty_additions.xml
@@ -0,0 +1,5 @@
+<vtydoc xmlns='urn:osmocom:xml:libosmocore:vty:doc:1.0'>
+    <node id='config-gbproxy'>
+	    <description>Configure the Gb proxy</description>
+    </node>
+</vtydoc>