Generate links to spec sections

[eagr]

One last fix for the compliance report.

Just realized that the target argument to duvet extract is also used as the reference/link in the comments that are generated from the compliance report, which should be used as is so that the comment will be treated as an effective citation. I guess for ergonomics, we should probably pass the spec link to duvet extract, instead of the local path of the spec txt. Am I missing anything? @camshaft

But then the action will need to fetch the spec page on every run. We could commit the extracted specs instead, if you prefer otherwise. @seanmonstar