Note history or blame log

To review note changes and revert.
It's necessary to have change history or blame log.

The issue names no files, tests, or entry points. Start by locating the note persistence and collaboration entry points, then determine the scope needed for reviewing changes and reverting a note; done means both change history or blame information and a working revert flow are defined and covered.

索引モデルが issue の本文から書いたものです。