changes: Add file for MR 835

Signed-off-by: David Goulet <dgoulet@torproject.org>

changes/ephemeral-onion-pow

+  o Minor feature (onion service, control port):
+    - Add 3 more keywords to the ADD_ONION control command: PoWDefensesEnabled,
+      PoWQueueRate and PoWQueueBurst which correspond to
+      HiddenServicePoWDefensesEnabled, HiddenServicePoWQueueRate and
+      HiddenServicePoWQueueBurst from torrc.
+
+