pep-0492: Add a sub-section about Async Lambdas

pep-0492.txt

@@ -811,6 +811,15 @@ for asynchronous comprehensions.  This should be considered in a separate PEP,
 if there is a strong demand for this feature.
 
 
+Async lambdas
+-------------
+
+Lambda coroutines are not part of this proposal.  In this proposal they would
+look like ``async lambda(parameters): expression``.  Unless there is a strong
+demand to have them as part of this proposal, it is recommended to consider
+them later in a separate PEP.
+
+
 Performance
 ===========