[Feature Request] CHANGELOG for `helm-charts` repo

[spanktar]

As a Platform Engineer responsible for deploying Temporal, I would like a CHANEGLOG.md in this repository so I can review changes before blindly upgrading. I know that I can use "compare" to see differences, but this is a collection of diffs with no context and difficult to follow.

For example, in this compare I learned that the app, admin-tools, and UI had all been upgraded, but the Releases page makes no mention of this.