manual: Use combined/merged gb-ns2 chapter

See https://gerrit.osmocom.org/c/osmo-gsm-manuals/+/30357

Depends: osmo-gsm-manuals I3c618e5af61b376435f400ef9c64245cec2f9b73
Change-Id: I881d8c2d400e47d9a39f8bd93668e1c3299e292f
diff --git a/doc/manuals/osmogbproxy-usermanual.adoc b/doc/manuals/osmogbproxy-usermanual.adoc
index 2a1b873..6bcba60 100644
--- a/doc/manuals/osmogbproxy-usermanual.adoc
+++ b/doc/manuals/osmogbproxy-usermanual.adoc
@@ -25,12 +25,6 @@
 
 include::./common/chapters/gb-ns2.adoc[]
 
-include::./common/chapters/gb-ns2-configuration.adoc[]
-
-include::./common/chapters/gb-ns2-configuration-timer.adoc[]
-
-include::./common/chapters/gb-ns2-maintenance.adoc[]
-
 include::./common/chapters/control_if.adoc[]
 
 include::./common/chapters/counters-overview.adoc[]