Add missing json output format help text

ChangeLog

@@ -1,3 +1,6 @@
+2018-02-11
+- Add missing json output format help text
+
 2018-01-06
 - Merge pull request #51 Influxdb from Luca. Thx for the patch
 

bin/nfdump.c

@@ -1,6 +1,5 @@
 /*
- *  Copyright (c) 2017, Peter Haag
- *  Copyright (c) 2014, Peter Haag
+ *  Copyright (c) 2018, 2017 Peter Haag
  *  Copyright (c) 2009, Peter Haag
  *  Copyright (c) 2004-2008, SWITCH - Teleinformatikdienste fuer Lehre und Forschung
  *  All rights reserved.
@@ -29,13 +28,6 @@
  *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
  *  POSSIBILITY OF SUCH DAMAGE.
  *  
- *  $Author: haag $
- *
- *  $Id: nfdump.c 69 2010-09-09 07:17:43Z haag $
- *
- *  $LastChangedRevision: 69 $
- *	
- *
  */
 
 #include "config.h"
@@ -311,6 +303,7 @@ static void usage(char *name) {
 					"\t\t long     Standard output line format with additional fields.\n"
 					"\t\t extended Even more information.\n"
 					"\t\t csv      ',' separated, machine parseable output format.\n"
+					"\t\t json     json output format.\n"
 					"\t\t pipe     '|' separated legacy machine parseable output format.\n"
 					"\t\t\tmode may be extended by '6' for full IPv6 listing. e.g.long6, extended6.\n"
 					"-E <file>\tPrint exporter ans sampling info for collected flows.\n"