Biomarker Assessed Entity ID Mapping

[kmartinez834]

I noticed on the Formatting/Contributing Data markdown, in the Biomarker Assessed Entity ID Mapping section, you have both "Carbohydrate" and "Glycan" as Assessed Entity Types. I recommend collapsing these into one "Glycan" entry as follows:

Assessed Entity Types	Resource (in order of preference/availability)
Glycan	GlyTouCan Accession (GTC) -> Chemical Entities of Biological Interest (ChEBI) -> PubChem (PCCID)

Note: GlyTouCan and ChEBI are sources for PubChem, so I would treat these as primary and PubChem as a secondary resource