Kozou v1.12.0

What's Changed

• Add an entity-relationship diagram to kozou docs by @takashi-matsuyama in #191
• Document that Kozou is migration-tool-agnostic by @takashi-matsuyama in #192
• release: v1.12.0 — entity-relationship diagram in kozou docs by @takashi-matsuyama in #193

Full Changelog: v1.11.0...v1.12.0