I notice that [there's an "--opt" flag](https://github.com/cljoly/into-ledger/blob/fbeb3d9469e598148e2e511231afc206ced6af42/main.go#L37), but [it's missing in `README.md`](https://github.com/cljoly/into-ledger/blob/fbeb3d9469e598148e2e511231afc206ced6af42/README.md#help).
