Add a pertinence extension

Add a pertinence extension to support identifying pertinence of elements included in the measure report. The extension url should be: http://hl7.org/fhir/us/cqfmeasures/StructureDefinition/cqfm-pertinence Model the extension the same as the cpg-caseFeaturePertinence extension: https://hl7.org/fhir/uv/cpg/StructureDefinition-cpg-caseFeaturePertinence.html The pertinence of the resource you are using to calculate the measure. You put this on evaluatedResource on a measure report.  For example, for a poorly controlled blood sugar, you can put A1c as pertinent on that measure report. This is what the pertinence is intended for. Will need example of measure report using pertinence extension.