Postman collection updates (#51)

* Added the Postman Collection JSON file

* Added a ‘Run in Postman’ button to the spec

* Removed the line that mentions ‘stateless’ etc…

* Updates to the Postman collection

* Updated the Postman ID

Author: adrianparr

specification/nhs-website-content-api.yaml

@@ -98,7 +98,7 @@ info:
 
     Alternatively, you can try out the sandbox using our Postman collection:
 
-    [![Run in Postman](https://run.pstmn.io/button.svg)](https://app.getpostman.com/run-collection/222854-9766f4d9-e6b9-41ec-8949-ef3758316de0)
+    [![Run in Postman](https://run.pstmn.io/button.svg)](https://app.getpostman.com/run-collection/222854-abafff02-a96d-4259-9c0d-2f4d3fd6d4bf)
 
     ### Integration testing
     Our [integration test environment](https://digital.nhs.uk/developer/guides-and-documentation/testing#integration-testing):