Correct a couple of unbalanced parenthesis. (GH-10779)

diff --git a/Doc/library/exceptions.rst b/Doc/library/exceptions.rst
index e33b886..57ed291 100644
--- a/Doc/library/exceptions.rst
+++ b/Doc/library/exceptions.rst
@@ -52,7 +52,7 @@
 :attr:`__cause__` also implicitly sets the :attr:`__suppress_context__`
 attribute to ``True``, so that using ``raise new_exc from None``
 effectively replaces the old exception with the new one for display
-purposes (e.g. converting :exc:`KeyError` to :exc:`AttributeError`, while
+purposes (e.g. converting :exc:`KeyError` to :exc:`AttributeError`), while
 leaving the old exception available in :attr:`__context__` for introspection
 when debugging.