Generalize documentation helpers

Change-Id: Iaba69a433f25d2160857694b0b434c51c02c0367
diff --git a/templates/doc/data.html.ep b/templates/doc/data.html.ep
index 4fd992c..514a461 100644
--- a/templates/doc/data.html.ep
+++ b/templates/doc/data.html.ep
@@ -1,14 +1,15 @@
 % layout 'main', title => 'KorAP: Data';
 
-<h2 id="tutorial-top">Data</h2>
+%= page_title
+
 <p>KorAP is developed as being the main access point to
-  <%= doc_ext_link_to 'DeReKo', 'http://www1.ids-mannheim.de/kl/projekte/korpora' %>,
-  being the successor of <%= doc_ext_link_to 'COSMAS II', 'https://cosmas2.ids-mannheim.de/cosmas2-web/' %> in that regard.
-  But KorAP is not focussed on any specific corpus, it is, for example, now also used for the Romanian national corpus <%= doc_ext_link_to 'CoRoLa', 'http://corola.racai.ro/' %>.</p>
+  <%= ext_link_to 'DeReKo', 'http://www1.ids-mannheim.de/kl/projekte/korpora' %>,
+  being the successor of <%= ext_link_to 'COSMAS II', 'https://cosmas2.ids-mannheim.de/cosmas2-web/' %> in that regard.
+  But KorAP is not focussed on any specific corpus, it is, for example, now also used for the Romanian national corpus <%= ext_link_to 'CoRoLa', 'http://corola.racai.ro/' %>.</p>
 
 <p>In KorAP, corpus texts are allowed to have arbitrary metadata information, that partially can be used to create subcorpora (so-called virtual corpora).</p>
 
-<p>KorAP also supports an arbitrary number of <%= doc_link_to 'Annotations', 'data', 'annotation' %> from different sources (called <em>foundries</em>) with different <em>layers</em>.</p>
+<p>KorAP also supports an arbitrary number of <%= embedded_link_to 'Annotations', 'data', 'annotation' %> from different sources (called <em>foundries</em>) with different <em>layers</em>.</p>
 
 <dl>
   <p>Annotations of the following kind are supported:</p>