Improve correctness and clarity of relative URLs for update subscriptions

[RubenVerborgh]

#181 (comment)
#181 (comment)

[michielbdejong]

OK, hadn't realised this would trigger a discussion, sorry. I though from the phrasing 'Some implementations do X' it was clear that this was not something the spec prescribes, just a footnote, but this was obviously not clear, apologies. I do want to write down somewhere that NSS does something different from what the spec prescribes, but maybe it's better to keep it outside the spec itself, and just create a github issue about it on the NSS repo

[RubenVerborgh]

I do want to write down somewhere that NSS does something different from what the spec prescribes

We should just determine what is right: should relative URLs be supported or not?
If yes, let's update the spec precisely; if no, NSS needs updating.

[michielbdejong]

Created nodeSolidServer/node-solid-ws#11 about updating NSS.

Sorry again for the confusion about process, I had intended this as just adding a remark in the margin, not changing the prescriptive text itself, that's why I hadn't looked for broader consensus on the text of my remark. Now that it's become clear that multiple people interpreted it as more than just a passing comment, I fully agree that both the process and the result went wrong here. Thanks for flagging it!