API spec - update postal code field indicating why it’s optional

https://developer.connect.gov.bc.ca/oas/br/model/address

**Tasks**

- [ ] Update [spec](https://github.com/bcgov/developer.connect/blob/main/web/site/public/br/business-spec.yaml) to make address optional. Add commentary around it being optional due to some countries not having postal codes.
- [ ] After spec PR merged in connect repo, make same updates to [LEAR repo spec file](https://github.com/bcgov/lear/blob/main/docs/business.yaml). Essentially just replace the file contents with whatever is in connect business api spec.