Improve AR changelog, add entry for migration error improvements #12462 [ci skip]

activerecord/CHANGELOG.md

@@ -1,8 +1,18 @@
-*   `Model.offset(4).last` now returns the 4th record from the end, not just last record.
+*   Improve formatting of migration exception messages: make them easier to read
+    with line breaks before/after, and improve the error for pending migrations.
+
+    *John Bachir*
+
+*   Fix `last` with `offset` to return the proper record instead of always the last one.
+
+    Example:
+
+        Model.offset(4).last
+        # => returns the 4th record from the end.
 
     Fixes #7441.
 
-    *kostya*
+    *kostya*, *Lauro Caetano*
 
 *   `type_to_sql` returns a `String` for unmapped columns. This fixes an error
     when using unmapped array types in PG