Build HTML from Ganeti 2.1 design

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>

Makefile.am

@@ -111,6 +111,7 @@ http_PYTHON = \
 docrst = \
 	doc/admin.rst \
 	doc/design-2.0.rst \
+	doc/design-2.1.rst \
 	doc/glossary.rst \
 	doc/hooks.rst \
 	doc/iallocator.rst \