Add note from 308

pep-3000.txt

@@ -74,6 +74,7 @@ Core language
 * List comprehensions will require parentheses around the iterables.
   This will make list comprehensions more similar to generator comprehensions.
   [x for x in 1, 2] will need to be:  [x for x in (1, 2)]
+* Lambdas will have to be parenthesized [23]_
 
 To be removed:
 
@@ -238,6 +239,9 @@ References
 .. [22] python-dev email ("defaultdict")
    http://mail.python.org/pipermail/python-dev/2006-February/061261.html
 
+.. [23] PEP 308 ("Conditional Expressions")
+   http://www.python.org/peps/pep-0308.html
+
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