"Blog: Security and multi-cloud (Nov 21)"

Closes #5822 (closed)

Slightly time sensitive – needs to publish this week (preferably Nov 21) to align with KubeCon

Checklist for writer

• Link to issue added, and set to close when this MR is merged
• Due date and milestone (if applicable) added for the desired publish date
• If time sensitive
  • Added ~"priority" label
  • Mentioned @rebecca to give her a heads up ASAP
• Blog post file formatted correctly, including any accompanying images
• All relevant frontmatter included
• Review app checked for any formatting issues
• Reviewed by fellow team member
• Assign to @rebecca for review

/label ~"blog post"