Clarify sub directories used by pkgutil extend_path in Docs

Author: Randy Pemberton

Doc/library/pkgutil.rst

@@ -25,9 +25,9 @@ support.
       from pkgutil import extend_path
       __path__ = extend_path(__path__, __name__)
 
-   This will add to the package's ``__path__`` all subdirectories of directories
-   on :data:`sys.path` named after the package.  This is useful if one wants to
-   distribute different parts of a single logical package as multiple
+   For each directory on :data:`sys.path` that has a subdirectory that matches the
+   package name, add the subdirectory to the package's :attr:`__path__`.  This is useful
+   if one wants to distribute different parts of a single logical package as multiple
    directories.
 
    It also looks for :file:`\*.pkg` files beginning where ``*`` matches the