Fix build issues

doc/develop.rst

@@ -100,7 +100,7 @@ This is the current list of contributed extensions in that repository:
 - zopeext: provide an ``autointerface`` directive for using `Zope interfaces`_
 
 
-See the :ref:`extension tutorial <exttuto-todo>` on getting started with writing your
+See the :doc:`extension tutorials <../development/tutorials/index>` on getting started with writing your
 own extensions.
 
 

doc/development/tutorials/helloworld.rst

@@ -150,13 +150,13 @@ You can now use the extension.
 
 This is the very basic principle of an extension that creates a new directive.
 
-For a more advanced example, refer to :ref:`exttuto-todo`
+For a more advanced example, refer to :doc:`todo`.
 
 Further reading
 ---------------
 
 You can create your own nodes if needed, refer to the
-:ref:`exttuto-todo` for more information.
+:doc:`todo` for more information.
 
 .. _docutils: http://docutils.sourceforge.net/
 .. _`docutils nodes`: http://docutils.sourceforge.net/docs/ref/doctree.html