Docs: Logstash 8.15.0 release docs

[karenzone]

Logstash release manager: TBD Logstash tech writer: @karenzone Docs release manager: TBD

Logstash release docs

• [ ] Day after FF, cut branches:
  • [ ] logstash
  • [ ] logstash-docs
  • [ ] ingest-docs
    • [ ] Update backport tolling for ingest-docs: Sample PR
• [ ] Release notes:
  • [ ] Add link to docs release issue:
  • [ ] Verify that release notes PR is forwardported to main:
• [ ] Update plugin docs:

Remember 🎗

• [ ] Update release notes and breaking changes for SNMP integration!
• [ ] Add info from @andsel Bundled JDK has been updated to 21