Load actual NCIT and MONDO codes for disease instances

[znatty22]

Branch off of the kf-model-fhir/add-phenopackets-model branch and create Pull Request against that branch

All of your conformance resource should go in: https://github.com/kids-first/kf-model-fhir/tree/add-phenopackets-model/site_root/source/resources

• [x] Modify Disease StructureDefinition - remove Condition.code (max cardinality to 0)
• [x] Create CodeSystem for all terms in MONDO -> CodeSystem-disease-term-mondo.json
• [x] Create CodeSystem for all terms in NCIT -> CodeSystem-disease-term-ncit.json
• [x] Create new Valueset to capture values from MONDO and NCIT CodeSystems -> ValueSet-disease-term.json
• [x] Create new extension for Disease called term -> StructureDefinition-disease-term.json
• [x] Bind ValueSet to Disease term extension
• [x] Bind new Disease term extension to Disease StructureDefinition
• [x] Create SearchParameter for Disease term extension -> SearchParameter-disease-term.json

[znatty22]

Closing since this is complete.