Include PRs without notes:ready in generated release notes #1202

Right now, when generating a release notes PR, if an included PR isn't labelled with notes:ready, we don't include the release notes at all. This means that for such PRs, the person writing the release notes has to manually copy the release notes from that PR.

I believe that most of the time, the absence of the notes:ready label just means that the PR author forgot to add the label. In any case, I think it's best if we included the PR's "Release Notes Summary" section in the generated release notes anyway. If the person writing the release notes doesn't like it, they can easily delete it.

This is the bit we need to touch. Easy peasy