Revert "Add clarification of handling of missing resources."

This reverts commit 246610dd.

src/Products/Five/browser/tests/resource.txt

@@ -69,17 +69,6 @@ PageTemplateResource's __call__ renders the template
   ...     if not isinstance(resource, PageTemplateResource):
   ...         self.assertEquals(resource(), base_url % r)
 
-Missing resources   
-~~~~~~~~~~~~~~~~~
-
-Looking up a missing resource raises a ``KeyError``, which the publisher
-then maps onto an HTTP 404 ("Not Found") response:
-
-  >>> self.folder.unrestrictedTraverse('testoid/++resource++nonesuch.txt')
-  Traceback (most recent call last):
-  ...
-  KeyError: ...
-
 Clean up
 --------