Break up What's Changed section for releases by library

[AjayKMehta]

Currently, when a release is created, the What Changed section lists changes across all libraries which makes finding changes for a specific library more cumbersome than it should be IMHO.

It would be nice if there were a sub-section per library highlighting changes applicable only to that library.

[stephentoub]

@jeffhandley has this been addressed as part of your recent process changes?

[jeffhandley]

Yes, it has. Thanks, @stephentoub. Fixed in #7390. Reflected in v10.3.0, v10.4.0, and v10.4.1.