RDT 293 Update Swagger documentation for Dataset access request and README file for data custodain email address

Created by: CMarksPA

Issue: With recent changes to the API the swagger documentation was out of date. The swagger yaml file has been updated to include the new parameters to post a dataset/access/request. Documentation has been updated to include correct types for datasets.

Important The README will contain a new variable which you need to add locally, this being DATA_CUSTODIAN_EMAIL this needs to be set to your personal email. PA email gets blocked depending on the server sendgrid use.