Update API docs to reflect relocation of pkg_resources from module to package.

pkg_resources/api_tests.txt

@@ -171,7 +171,7 @@ You can append a path entry to a working set using ``add_entry()``::
     ['http://example.com/something']
     >>> ws.add_entry(pkg_resources.__file__)
     >>> ws.entries
-    ['http://example.com/something', '...pkg_resources.py...']
+    ['http://example.com/something', '...pkg_resources...']
 
 Multiple additions result in multiple entries, even if the entry is already in
 the working set (because ``sys.path`` can contain the same entry more than