manual: Fix documentation missing "-D" command line option

Change-Id: I2fd0b6f52ddc6931f413921b45d9756cb1fe456d
diff --git a/doc/manuals/chapters/running.adoc b/doc/manuals/chapters/running.adoc
index 6a52b70..d7e6383 100644
--- a/doc/manuals/chapters/running.adoc
+++ b/doc/manuals/chapters/running.adoc
@@ -15,8 +15,8 @@
 	Print a short help message about the supported options
 *-V, --version*::
 	Print the compile-time version number of the program
-//*-D, --daemonize*::
-//	Fork the process as a daemon into background.
+*-D, --daemonize*::
+	Fork the process as a daemon into background.
 *-c, --config-file 'CONFIGFILE'*::
 	Specify the file and path name of the configuration file to be
 	used. If none is specified, use `osmo-pcu.cfg` in the current