It used to be a common thing to have to update Config.md in a PR (and we often
forgot despite the template). As of #3565 this is no longer necessary, so remove
this from the template.
Updating docs in general is still a good thing to think about, so we leave this
in.
This spares me effort when it comes to making release notes.
Yes, sometimes it may be easier to start a message without an imperative e.g. 'When X happens, do Y'
but I don't want to overwhelm the contributor with details.
