Use spec-prod to publish spec drafts

[jyasskin]

As you start working on a more formal specification, it'll be easier to keep the editor's draft up to date if you install the github actions from https://w3c.github.io/spec-prod/ instead of needing to check in the generated index.html with each change.

[anssiko]

We should also move from master to main branch on the same pass.

cc @dontcallmedom

[dontcallmedom]

done in #10 and associated repo changes

[anssiko]

Thanks @dontcallmedom!

@jbingham here’s the dance needed to sync local copies:

$ git checkout master
$ git branch -m master main
$ git fetch
$ git branch --unset-upstream
$ git branch -u origin/main
$ git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/main

Or alternatively clone a new fresh copy.

[jbingham]

Thanks!