make KorAP instance configurable

see example.conf

Change-Id: Ia6ece608272cf21efba29e23f948434164487f3d
diff --git a/script/derekovecs-server b/script/derekovecs-server
index dfabae7..75b29b4 100755
--- a/script/derekovecs-server
+++ b/script/derekovecs-server
@@ -16,6 +16,8 @@
 plugin Config => {file => $mojo_config};
 
 my $DEFAULT_VECS = app->config->{w2v}->{vecs} // "../models/dereko-2021-i.vecs";
+my $KORAP_URL = app->config->{w2v}->{korap_url} // "https://korap.ids-mannheim.de";
+
 my $DEFAULT_NET_NAME = "";
 if ($DEFAULT_VECS=~ /\.vecs/) {
   $DEFAULT_NET_NAME = $DEFAULT_VECS;
@@ -406,6 +408,7 @@
       lists                => \@lists,
       collocators          => $res->{syntagmatic},
       version              => $VERSION,
+      korap_url            => $KORAP_URL,
     );
   }
 } => "paradigmaticAndSyntagmaticNbs";