Add CHANGELOG entry

CHANGELOG.md

@@ -20,6 +20,16 @@
 
   ([PR #N](https://github.com/alphagov/govuk-frontend/pull/N))
 
+- Ability to group radio buttons/checkboxes within sub-headings
+
+  All form fields are now wrapped in `govukFormGroup()` to generate the appropriate hint, error message, fieldset and legend (or label).
+
+  The new wrapper can be used to `call` in other components to support a top-level fieldset with multiple nested components.
+
+  Nested fieldsets can now receive the `describedBy` parameter to persist error message and hint relationships from the parent fieldset.
+
+  ([PR #1266](https://github.com/alphagov/govuk-frontend/pull/1266))
+
 🔧 Fixes:
 
 - Pull Request Title goes here