documentation: drop a link that doesn't work

This whole thing will be dropped soon via MR !120

content/pages/en/documentation.rst

@@ -23,9 +23,7 @@ Offline documentation is also available in *knot-resolver-doc* package for most
 distributions.
 
 *Read the Docs* also offers downloads of
-`PDF <https://readthedocs.org/projects/knot-resolver/downloads/pdf/stable/>`__,
-`HTML
-archive <https://readthedocs.org/projects/knot-resolver/downloads/htmlzip/stable/>`__,
+`PDF <https://readthedocs.org/projects/knot-resolver/downloads/pdf/stable/>`__
 and
 `EPUB <https://readthedocs.org/projects/knot-resolver/downloads/epub/stable/>`__
 formats for viewing offline.