Add comment policy to the blog

Add a comment policy to the blog above the comment field so it'll be visible on each post beneath "Join the discussion."

Note: only "join the discussion" remains visible from the blog archive. The new text is only visible inside each post.

"Join the discussion...

We encourage respectful, on-topic comments. Comments that violate our Code of Conduct will be deleted. Off-topic comments may be deleted at the discretion of the post moderator. Please do not comment as a way to receive support or report bugs on a post unrelated to a release. If you are looking for support, please see our support portal or ways to get in touch with us.