Add USCore

Add USCore

Author: KazeemHamzat

private.package.yaml

@@ -28,7 +28,12 @@ implementationguides:
         version: 0.1.1-alpha
         installMode: STORE_AND_INSTALL
         fetchDependencies: false
-      hl7-fhir-us-mcode:
+      hl7.fhir.us.core:
+        name: hl7.fhir.us.core
+        version: 6.1.0
+        installMode: STORE_AND_INSTALL
+
+      hl7.fhir.us.mcode:
         name: hl7.fhir.us.mcode
         version: 4.0.0
         installMode: STORE_AND_INSTALL