Replace rel=self with rel=canonical #68
Description
WebSub requires each resource to be delivered with a rel=self link:
Link Headers [RFC5988]: the publisher SHOULD include at least one Link Header [RFC5988] with rel=hub (a hub link header) as well as exactly one Link Header [RFC5988] with rel=self (the self link header)
The web is already adding links to the resource itself in HTML pages, it's the rel=canonical link which is supported by major search engines since 2009.
I do not see a reason to add a second link that has the same meaning. Please drop rel=self and replace it with rel=canonical.
See https://chat.indieweb.org/2015-05-22#t1432330810734000 for a discussion in die #indieweb channel about this:
tantek: however, this "even if the same resource is served at http, https, /, and /index.html, only one of those URls actually works as the push topic" - is an already solved problem
search engines have the same problem
and previously solved it with rel=canonical
thus if that really is a problem for PuSH as well, the PuSH should build upon the pre-existing rel=canonical for the page, rather than require rel=self