docs: note IPv6 support in systemd

[GabriellePoncey]

Summary

Docker Swarm does not currently support IPv6 addressing, but the
prerequisites page didn't call this out anywhere. r.

Changes

• Add a bullet next to the existing IP/hostname prerequisite clarifying that IPv6 hosts require the systemd orchestrator

PLAT-675

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 89ee3f96-dd5a-41c9-9498-ec44d2e8a6d6

📥 Commits

Reviewing files that changed from the base of the PR and between 5b23623 and af3684b.

📒 Files selected for processing (1)

• docs/prerequisites/index.md

🚧 Files skipped from review as they are similar to previous changes (1)

• docs/prerequisites/index.md

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📝 Walkthrough

Walkthrough

The prerequisites documentation specifies that IPv6 addresses are supported with the systemd orchestrator, while Docker Swarm does not currently support pure IPv6.

Changes

IPv6 documentation

Layer / File(s)	Summary
Document orchestrator IPv6 support docs/prerequisites/index.md	Adds a prerequisite bullet clarifying IPv6 support for systemd and its lack of support for pure IPv6 in Docker Swarm.

Poem

I’m a rabbit with an IPv6 route,
Hopping where systemd lets packets sprout.
Docker Swarm waits by the door,
Pure IPv6 won’t hop ashore.
Clear docs help my carrots grow!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise, conventional, and matches the IPv6 prerequisite docs update.
Description check	✅ Passed	Summary and Changes are present and relevant, with an issue reference, though Testing, Checklist, and Notes sections are missing.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/PLAT-675/systemd-ipv6-doccumentation

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Up to standards ✅

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@docs/prerequisites/index.md`:
- Line 7: Update the IPv6 prerequisite statement in the documentation to scope
the Docker Swarm limitation specifically to deployments using pure IPv6 host
addresses, where host peer/client detection requires or advertises IPv4. Do not
imply that Docker Swarm cannot handle IPv6 CIDR allocation generally, and retain
the systemd support guidance.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 13b5fb73-f22c-4baf-8d13-76781b7b27f1

📥 Commits

Reviewing files that changed from the base of the PR and between d97a20c and 5b23623.

📒 Files selected for processing (1)

• docs/prerequisites/index.md