If possible, it would seem to be better for the coming several months to have links go to the github pages from which one can then find the PDF and/or adoc of the latest draft of the document.  Then links won't go stale.

Although when the Platform Specs go to public review they will need to be up-to-date links (if they aren't simply to the github page with the latest draft spec).  And since lots of parallel public reviews will be happening this fall, any spec cross-references are going to be to unratified draft specs (albeit frozen).