Is your feature request related to a problem? Please describe.
As an API governance architect, we have a number of design decisions enforced with Redocly rules. While we try to make the rules self-documenting, there are definitely some instances which require a deeper context on the decision.

Describe the solution you'd like
I would like a property to include an external link to documentation supporting the design decision of a particular rule so a user of the linter can find reference material for the rule.

{
    "message": <string>,
    "location": Location{},
    "suggest": <string>[],
    "from": Location{},
    "reference": <string><uri-reference>
}

Describe alternatives you've considered
I'm currently trying out \n\t formatting in the message body but I would like something more formal.

report({
      message: `this is a message with a reference to external docs\n\treference: https://www.redocly.com`
      })

  1:1  warning  custom-id/some-rule  this is a message with a reference to external docs
        reference: https://www.redocly.com