fix copy&paste errors in docstrings

Author: michael-koeller

docx/opc/customprops.py

@@ -1,8 +1,7 @@
 # encoding: utf-8
 
 """
-The :mod:`pptx.packaging` module coheres around the concerns of reading and
-writing presentations to and from a .pptx file.
+Support reading and writing custom properties to and from a .docx file.
 """
 
 from __future__ import (

docx/opc/package.py

@@ -45,8 +45,8 @@ def core_properties(self):
     @property
     def custom_properties(self):
         """
-        |CustomProperties| object providing read/write access to the Dublin
-        Core properties for this document.
+        |CustomProperties| object providing read/write access to the 
+        custom properties for this document.
         """
         return self._custom_properties_part.custom_properties