Tutorial: rename "Data" to "Corpus Data" in navigation bar and headline

Change-Id: I98a7ad482008972f73180529872dfaf656d33eae
diff --git a/templates/doc/data.html.ep b/templates/doc/data.html.ep
index eec65a1..237e851 100644
--- a/templates/doc/data.html.ep
+++ b/templates/doc/data.html.ep
@@ -1,4 +1,4 @@
-% layout 'main', title => 'KorAP: Data';
+% layout 'main', title => 'KorAP: Corpus Data';
 
 %= page_title