Improve blog contributing guide for release feature blogs

[a-mccarthy]

This is a Feature Request

We should update https://kubernetes.io/docs/contribute/new-content/blogs-case-studies/ to include better information around
writing feature blogs for a release.

We should provide better guidance around when a blog is needed for a KEP and any special guidance for writing release blogs.

What would you like to be added

• Include a list of guidelines for KEP owners to understand when we'd recommend writing a blog for a upcoming feature
• Include formatting changes for feature blogs, like using XX placeholder dates and that publication dates are determined by the release comms team.

Why is this needed

There is currently very little guidance around when someone should write a feature blog for a release. This can be hard for KEP owners as well as release comms team members bc it relies on those folks having more context and depth of knowledge that can be reasonably assumed.

Comments

/area blog

[a-mccarthy]

/assign

[sftim]

/triage accepted

[sftim]

also just about
/area release-eng

I think

[sftim]

/sig release