Update changelog.

CHANGES.rst

@@ -73,6 +73,11 @@ Features added
 Bugs fixed
 ----------
 
+* The exception handling in generators and coroutines under CPython 3.7 was adapted
+  to the newly introduced exception stack.  Users of Cython 0.28 who want to support
+  Python 3.7 are encouraged to upgrade to 0.29 to avoid potentially incorrect error
+  reporting and tracebacks.
+
 * Crash when importing a module under Stackless Python that was built for CPython.
   Patch by Anselm Kruis.  (Github issue #2534)