Link Relation Type for Workflows

[frankkilcommins]

In conversations with Erik Wilde, we also think it sensible that there should be a link relation
type for workflows, so that for example an OpenAPI document could link
to workflows.

[adamaltman]

This could be handled initially through specification extension. At what level would the link occur (root, operation, etc)? Would it link to a specific workflow ID or to an entire workflow document? (Some first questions that come to mind for future discussion.)