Add HIPPS Code Set to us-core-procedure-code to enable use of HIPPS codes for Procedures referenced by CARIN Consumer Directed Payer Data Exchange and Payer Data Exchange IGs. 

It is more efficient to update the extensible US Core Procedure Codes Value Set in US Core and avoid the CARIN and PDex guides from profiling US Core Procedure in the same way to accommodate payer needs under the CMS Interoperability Rule regarding the publishing of data under the Patient Access API.

Details about the code set can be found here:

https://www.cms.gov/Medicare/Medicare-Fee-for-Service-Payment/ProspMedicareFeeSvcPmtGen/HIPPSCodes