docs: add integration guidance and Range42

[pparage]

Summary

• add implementation-neutral guidance for consuming the exercise-world dataset safely
• recommend pinning the exact misp-galaxy cluster and galaxy revision, using stable UUID references, loading the galaxy before tagged events, and preserving attribution
• list the Range42 integration as work in progress with links to its public tracking issue and implementation PRs

Why

The SEWF version alone does not identify the exact misp-galaxy files a deployment consumes. Documenting revision pinning and validation helps downstream integrations avoid silent UUID or metadata drift while keeping the guidance useful beyond Range42.

Range42 work

• Tracking: https://github.com/range42/project_management/issues/106
• Catalog implementation: feat(exercise-world): package Nacre and seed MISP range42/range42-catalog#211
• Scenario binding: feat(misp_lab): bind Nacre world metadata range42/range42-playbooks#151

Validation

• git diff --check
• documentation-only change