Update the 3.2.0 changelog for config update notification (#187)

rashidsp · aliabbasrizvi · commit 6a1eec32be80 · 2019-09-04T12:05:41.000-07:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -13,6 +13,7 @@ August 28th, 2019
   ```
   $configManager->fetch();
   ```
+  * Configuration updates can be subscribed to by adding the `OPTIMIZELY_CONFIG_UPDATE` notification listener.
 
 ## 3.1.0
 May 3rd, 2019
