r3.stats: added 'volume' keyword

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@71127 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster3d/r3.stats/main.c

@@ -1,7 +1,7 @@
 /*
  *   r3.stats
  *
- *   Copyright (C) 2004-2007 by the GRASS Development Team
+ *   Copyright (C) 2004-2017 by the GRASS Development Team
  *   Author(s): Soeren Gebbert
  *
  *   Purpose: Generates volume statistics for raster3d maps.           
@@ -48,6 +48,7 @@ int main(int argc, char *argv[])
     G_add_keyword(_("raster3d"));
     G_add_keyword(_("statistics"));
     G_add_keyword(_("voxel"));
+    G_add_keyword(_("volume"));
     module->description = _("Generates volume statistics for 3D raster maps.");
 
     /* Define the different options */