r.watershed: remove duplicate param description

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@59637 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.watershed/front/main.c

@@ -147,9 +147,7 @@ int main(int argc, char *argv[])
 
     opt10 = G_define_standard_option(G_OPT_R_OUTPUT);
     opt10->key = "basin";
-    opt10->description =
-	_("Name for basins raster map");
-    opt10->description = _("Unique label for each watershed basin");
+    opt10->description = _("Name for basins raster map");
     opt10->required = NO;
     opt10->guisection = _("Outputs");