Fix KONVENS typo

Change-Id: I06b82b1710f1f10f818c5d50eb607fd1e7e4ed12
diff --git a/perl/extractbench.pl b/perl/extractbench.pl
index cf21012..155a783 100644
--- a/perl/extractbench.pl
+++ b/perl/extractbench.pl
@@ -1,7 +1,7 @@
 use strict;
 use utf8;
 
-# usage: perl extractbench.pl konventsin.tsv konventsout.tsv
+# usage: perl extractbench.pl konvensin.tsv konvensout.tsv
 
 my $input  = $ARGV[0];
 my $output = $ARGV[1];