Clojurians Log v2

@grounded_sage there's this guide https://github.com/replikativ/datahike/blob/main/doc/schema-migration.md by @timok

I haven't had the guts to run one. I've a whole bunch of post processing. I'll try one once I've merged a more robust backup and restore mechanism into datahike

@grounded_sage When you do a "migration", what happens (AFAICT) is your entire db is reconstituted—every transaction in the history of your db is executed or “replayed”.