Proposal recipe / blog post for guide about disabling Keystatic routes in Astro prod

[simonswiss]

Proposal for incorporation of the "disabled Keystatic Admin UI routes in prod" content from #545

Recipe here: https://keystatic-site-git-blog-and-recipe-thinkmill-labs.vercel.app/docs/astro-disable-admin-ui-in-production

Blog post here: https://keystatic-site-git-blog-and-recipe-thinkmill-labs.vercel.app/blog/astro-preventing-indexing-of-keystatic-admin-ui-routes-in-production

[changeset-bot]

⚠️ No Changeset found

Latest commit: 085b1ac

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
keystar-ui	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 4, 2023 7:32am
keystatic	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 4, 2023 7:32am
keystatic-site	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 4, 2023 7:32am