Minor tweaks to dataclasses docs. (GH-6903)

diff --git a/Doc/library/dataclasses.rst b/Doc/library/dataclasses.rst
index 489dece..a90fcf7 100644
--- a/Doc/library/dataclasses.rst
+++ b/Doc/library/dataclasses.rst
@@ -1,8 +1,8 @@
-:mod:`dataclasses` --- Dataclasses
-==========================================
+:mod:`dataclasses` --- Data Classes
+===================================
 
 .. module:: dataclasses
-    :synopsis: Generate special methods and add to user-defined classes.
+    :synopsis: Generate special methods on user-defined classes.
 
 .. moduleauthor:: Eric V. Smith <eric@trueblade.com>
 .. sectionauthor:: Eric V. Smith <eric@trueblade.com>