We need a page in sphinx/generators for the gen-prefix-map command

We have this page:

https://linkml.io/linkml/generators/jsonld-context.html

However, json-ld 1.1 is quite complex and many consumers want a simple yaml prefix mapping, see biolink/biolink-model#710