`removeBatch` and `concat` are missing in type definitions

[IgorRain]

Are you submitting a bug report or a feature request?

bug report?

What is the current behavior?

There are two missing functions definitions in FieldArrayRenderProps interface removeBatch and concat (index.d.ts). This functions are defined in Final Form Arrays API. They are actually there at runtime, just "invisible" for TypeScript users.

What is the expected behavior?

Definitions in FieldArrayRenderProps should match Final Form Arrays API.

[IgorRain]

Both of these functions also never mentioned in the README.md. Is this on purpose?