OsmoGSMTester: use proper systemd service names

* use osmo-bts-sysmo for sysmoBTS systemd service name which is available
  since 114293a414bd5b7c86622ec8c293c4034c80d243
* use osmo-pcu for OsmoPCU systemd service name which is available since
  241f5bcb00f9c6fee4200a3aea9aa497bf0d3eee

Change-Id: Ie017946b9099460ac6758ff84ec7a10df13390a1
diff --git a/doc/manuals/chapters/install.adoc b/doc/manuals/chapters/install.adoc
index 0c69dcd..f58c611 100644
--- a/doc/manuals/chapters/install.adoc
+++ b/doc/manuals/chapters/install.adoc
@@ -541,7 +541,7 @@
 be disabled:
 
 ----
-systemctl mask osmo-nitb sysmobts sysmopcu sysmobts-mgr
+systemctl mask osmo-nitb osmo-bts-sysmo osmo-pcu sysmobts-mgr
 ----
 
 This stops the stock setup keeping the BTS in operation and hence allows the