added version option to the man page

doc/stdd.1

@@ -32,6 +32,9 @@ instructs stdd to drop privileges and run with the privileges defined user. Plea
 .TP
 .BI "-c --config " "configuration file"
 define the path to your stdd configuration file. This is usually needed to start the program in both modes.
+.TP
+.BI "--version"
+print version information and exit.
 .SH EXAMPLES
 .TP
 .B stdd -c /etc/stdd.conf