Enhance API spec

[Denny-g6labs]

ACH Version

Enhance the API spec with useful information such as max length and so on by respecting the official doc:
https://achdevguide.nacha.org/ach-file-details

What were you trying to do?

Use the API properly.

What did you expect to see?

• maxLength
• pattern
• maximum
• enum
• maxItems
• minimum

[adamdecaf]

Yea this would be helpful!