[META] Detection and Response docs checklist

[jmikell821]

Related issue: https://github.com/elastic/security-team/issues/437

• Updates to rule actions API
• Support MITRE ATT&CK subtechniques in rule creation
• Prebuilt rules for 7.11
• Exception list features
• Detections Migration API
• Add support for exceptions to ML Rules
• Add section on using Value Lists with Indicator Match Rules
• Update Detections permissions to include maintenance for .siem-signals* index
• Document Detection Engine compatibility with Cold Tier storage and Searchable Snapshots
• List of API changes for 7.11
• Add alert source to detection rule action context
• Add example of "current element' in alert placeholders