MusicBee Version 3.5.8730
.8730, as you said, is a patch version and as such, no release notes are readily available. Typically a patch version fixes a bug or enhances an existing feature/option. You'll have to follow most of the forum threads to see what comments have been made when Steven issues a patch.
Full release notes are published when Steven issues a full release. Those are always found in the first forum topic for the current release cycle.
EDIIT: typo