Improved documentation to be more precise regarding non-argument calls (thx @margaretha)

Change-Id: Ic80abd036ae66f9224063be747df3dcc248a1755
diff --git a/t/script/extract.t b/t/script/extract.t
index 8e7cdfd..0f8f0b7 100644
--- a/t/script/extract.t
+++ b/t/script/extract.t
@@ -31,7 +31,7 @@
   sub {
     system($call);
   },
-  qr!extract.+?Extract KorAP-XML files!s,
+  qr!extract.+?Extracts KorAP-XML files!s,
   $call
 );