The readme says:

transaction

transaction is useful if you need to run some SQL which cannot be executed from within a transaction. For example, in Postgres, you would need to disable transactions for migrations that alter an enum type to add a value

I was surprised to read this, as it hasn't been my experience. Turns out adding enum values has worked within transactions since v12 (released 2019).

Might want to add a note that this only applies to super old versions of PG or come up with an example where it's still relevant.