Subsets clean-up in EDAM: reflect in docs

[matuskalas]

Corresponding issue in EDAM: edamontology/edamontology#418 and in validator: edamontology/edamxpathvalidator#14

• Every data_|format_|operation_|topic_ concept has data|format|operation|topic subset
• Everything in the mainline EDAM needs subset bio
• Subsets are encoded in a desired way, ideally (Semantic) Web-friendly. Needs some more experiments first...