Enhance rollouts documentation

[jaredlockhart]

Summary

The existing rollouts article needs an enhancement pass to better organize the content, fill in technical gaps, and bring it up to the same quality level as the new Firefox Labs article.

Current gaps

• Live update workflow: The article mentions live editability but doesn't explain the full request-update → review → approve → sync workflow, or the "dirty" state
• Rollout lifecycle: No mention that rollouts skip the observation phase (enrollment → complete), or that rollouts cannot end enrollment (unlike experiments)
• Pref conflict handling: prevent_pref_conflicts is always forced for rollouts but not documented
• Rollout bucketing warnings: Duplicate rollout detection for same feature/channel/targeting not mentioned
• No results/analysis: Article mentions OpMon but doesn't clearly state that rollouts have no statistical analysis or results page
• Promote to Rollout: Mentioned briefly but could use more context about what gets cloned and reset
• Supported platforms/versions: Minimum version info is outdated (links to source code rather than stating values)

Approach

Reorganize and expand the article following the structure of the Firefox Labs article, with clear sections for what/when/how and verified technical details from the Experimenter codebase.