docs: fix conformance numbers, add known limitations and security note

[vieiralucas]

Summary

• Fix conformance claim: 16/18 services at 100% (was incorrectly stated as 19)
• Add performance measurement methodology after comparison table
• Document known limitations (SNS email/SMS stubs, CloudWatch Logs anomaly detection)
• Add Docker socket security note for Lambda/RDS/ElastiCache container features
• Add AGPL license clarification for dev/test usage
• Fix website service count (21 → 22)
• Add StepFunctions to EventBridge cross-service target list

Test plan

• No code changes, docs only
• CI green

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Summary by cubic

Fixes the conformance claim and tightens docs for accuracy and security. Adds performance measurement notes, known limitations, and small corrections to targets and service counts.

• Docs
  • Correct conformance stats to 16/18 tested services; update website service count to 22.
  • Add performance measurement methodology under the comparison table.
  • Document known limitations: SNS email/SMS stubs; CloudWatch Logs anomaly detection not executed.
  • Add Docker socket security note for Lambda/RDS/ElastiCache containers and clarify AGPL-3.0 usage for dev/test.
  • Include StepFunctions in the EventBridge cross-service target list.

^{Written for commit 216bd3e. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 2 files