Update changelog

railties/CHANGELOG.md

@@ -1,3 +1,18 @@
+*   Add customized prompt for Rails console
+
+    Currently, Rails console uses the default IRB prompt, which makes it easily
+    confused with normal IRB sessions and the prompt is not helpful for Rails development.
+
+    The new Rails console prompt is shorter and shows its environment:
+
+    ```txt
+    dev:001> # for develoment
+    prod:001> # for production
+    test:001> # for test
+    ```
+
+    *Stan Lo*
+
 *   Ensure `autoload_paths`, `autoload_once_paths`, `eager_load_paths`, and
     `load_paths` only have directories when initialized from engine defaults.
     Previously, files under the `app` directory could end up there too.