Spec changelog + function for migration

[AlphaJack]

Hi, I was wondering about two points:

• is there a changelog that highlights the new features in 0.2 compared to 0.1? (e.g. parquet file names)
• should there be a "maintenance" function to manually migrate a DuckLake 0.1 instance to the most recent standard version, instead of automatically trying to migrate on extension loading?

[ben-burwood]

FYI #319 PR combats point 2 to prevent DuckLake from Automatically Migrating