Remove this todo from release branch for now so it doesn't block point release. …

Remove this todo from release branch for now so it doesn't block point release.  (It is actually a todo for 0.5 that came back in a cherry-pick.)

c++/src/kj/exception.h

@@ -125,7 +125,6 @@ private:
   friend class ExceptionImpl;
 };
 
-// TODO(soon):  These should return StringPtr.
 ArrayPtr<const char> KJ_STRINGIFY(Exception::Nature nature);
 ArrayPtr<const char> KJ_STRINGIFY(Exception::Durability durability);
 String KJ_STRINGIFY(const Exception& e);