Fix typo

src/apps/relay/mainrelay.c

@@ -464,7 +464,7 @@ static char Usage[] = "Usage: turnserver [options]\n"
 " -v, --verbose					'Moderate' verbose mode.\n"
 " -V, --Verbose					Extra verbose mode, very annoying (for debug purposes only).\n"
 " -o, --daemon					Start process as daemon (detach from current shell).\n"
-" --systemd					Notify systemd about server status. (Use only in forground!)\n"
+" --systemd					Notify systemd about server status. (Use only in foreground!)\n"
 " --no-software-attribute	 		Production mode: hide the software version (formerly --prod).\n"
 " -f, --fingerprint				Use fingerprints in the TURN messages.\n"
 " -a, --lt-cred-mech				Use the long-term credential mechanism.\n"