Add a pre-publish checklist

[picocodes]

Discussed in https://github.com/hizzle-co/noptin/discussions/765

^{Originally posted by scrobbleme February 16, 2024} Hello,

Currently the post date is used for the sending the newsletter.

This is quite dangerous, as this is not obvious. People tend to just click "publish" and the newsletter is send.

Better would be a

• required
• extra field

This way people have to knowingly select a future date.