Keep change log up to date.

CHANGES.md

@@ -1,13 +1,25 @@
 ## Unreleased
 
+#### Breaking 
+
+  - [#357](https://github.com/Day8/re-frame/pull/357)
+    I'd be amazed if this actually broke any apps. Shocked. But for completeness ... the 
+    effect handler for `:db` has been changed. If the provided value tests 
+    `identical?` to the current value within `app-db` then `app-db` is not `reset!`. 
+    Previously, `app-db` was always `reset!` when a `:db` effect was supplied, 
+    which caused Layer 2 subscriptions to run unnecessarily. So this is a tiny 
+    efficiency change which also results in behaviour that better matches 
+    programmer intuitions.
+
 #### New
 
-  - improved [testing docs](https://github.com/Day8/re-frame/blob/master/docs/Testing.md)
-  - added [a new mental model](https://github.com/Day8/re-frame/blob/master/docs/MentalModelOmnibus.md#on-dsls-and-machines)
-  - Enshrine and document existing practice around `dispatch-n` and `nils` [checkin](https://github.com/Day8/re-frame/commit/6efdae438f393f8121a2d6dfbf76db00e6dafbf5)
-#### Fixes
+  - added [testing docs](/docs/Testing.md)
+  - added [a new mental model](/docs/MentalModelOmnibus.md#on-dsls-and-machines)
+  - added [a new FAQ](docs/FAQs/When-Does-Dispatch-Happen.md) on dispatch processing 
+  - The effect `:dispatch-n` will now ignore `nils` which can be useful. [See checkin](https://github.com/Day8/re-frame/commit/6efdae438f393f8121a2d6dfbf76db00e6dafbf5)
+
+#### Fixes and Improvements
 
- - [#357](https://github.com/Day8/re-frame/pull/357)
  - [#340](https://github.com/Day8/re-frame/pull/340)
  - [#341](https://github.com/Day8/re-frame/pull/341) Fix `re-frame.std-interceptors/on-changes` to work even if effect handler does not set `:db`.