Preparing release notes for a client means listing every X++ and binary hotfix that went into a release — and LCS has no feature to export that information in bulk. I spent a painful amount of time extracting descriptions one hotfix at a time before finding a better way.
If you're in the same spot, try 2LCS by Tomek Melissa. It's not a Microsoft-supported release, so use it at your own risk — but it works, and it does more than just this one job.