Add more context on the Release Notes landing page (#19456)

* Add little more verbiage on the Release Notes landing page

* Add missing comma

website/content/docs/release-notes/index.mdx

@@ -7,3 +7,11 @@ description: Release notes for new Vault versions.
 # Release Notes
 
 Release notes describe major updates in new versions of Vault.
+
+Choose a version from the navigation sidebar to view the release notes for each
+of the major software packages in the Vault product line.
+
+Please refer to the
+[Changelog](https://github.com/hashicorp/vault/blob/main/CHANGELOG.md) for
+further information on product improvements, including a comprehensive list of
+bug fixes.