Recommend property to connect markup to profile to which it conforms

[AlasdairGray]

A property is required to let consuming applications know which Bioschemas Profile it complies with, and specifically which version. This is related to #294 which recommends that @id and @type are included in the boilerplate template, but wanted to capture in its own issue to ensure that it doesn't get forgotten.

Boilerplate for Bioschemas markup should include a link to the profile against which the markup complies. The dcterms:conformsTo property has been used for a couple of years now for this purpose and is included in the template markup from the BioschemasGenerator.

[stain]

See also #297

[AlasdairGray]

The below screenshot shows what is being proposed as part of #294