Publishing docs: apply miscellaneous edits

[ddbeck]

I just did a web-features release and made a few improvements to the publishing docs as I went. Hopefully this stuff will help me complete it a little faster next time:

• Explain where we're checking for unescaped HTML
• Provide Markdown literals for pasting into the release description
• Add follow up step for "version required" labels
• Add a regex hint for creating releases
• Use full stops consistently
• Number the steps

[Elchi3]

Thanks Daniel! Maybe someone other than you should at release the package to see if the docs are useful enough. This reads good to me, though!

[ddbeck]

Yes, I agree that would be good to do—though I have some more changes to follow up to this. Luckily, Philip wrote the original text and I learned to release from it, so the foundations are solid.