docs: add Datacenter access section (Netbird VPN + board access)

[igorpecovnik]

Adds a Datacenter access page under CONTRIBUTE for board maintainers who need to reach the hardware lab.

What's covered

• VPN via Netbird — install the client and netbird up --management-url https://netbird.armbian.com; authentication is via GitHub, gated to the board-maintainers team.
• Accessing boards — look them up in NetBox (netbox.armbian.com) and SSH to their IP.
• Boards list — scaffolded with <!-- BOARDS-START --> / <!-- BOARDS-STOP --> markers and a placeholder, to be auto-updated via PR from NetBox (same mechanism as the wireless-performance table). The CI generator is a follow-up.

Please sanity-check the specifics

I wrote the Netbird steps from the standard self-hosted GitHub-SSO flow; confirm these match the real setup:

• Management URL is exactly https://netbird.armbian.com (no custom port)?
• The Linux install one-liner (pkgs.netbird.io/install.sh) is the method you want to recommend?
• SSH access: I left the login generic (ssh <user>@<board-ip>, e.g. root@10.0.50.42) since I didn't want to invent credentials/key handling — tell me the actual login (root? per-maintainer key?) and I'll make it exact.

Follow-up

Want me to build the NetBox→PR generator (in autotests) that fills the Boards table between the markers, like the iperf/wireless doc PR? I can wire it up next.

Documentation website preview will be available shortly:

 Open WWW preview 

[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

Run ID: aa36e9cf-0301-44a4-9c20-0caddb42c8b0

📥 Commits

Reviewing files that changed from the base of the PR and between 835168c and fee8958.

📒 Files selected for processing (1)

• docs/Contribute/Datacenter.md

✅ Files skipped from review due to trivial changes (1)

• docs/Contribute/Datacenter.md

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Walkthrough

This pull request adds a new documentation page, docs/Contribute/Datacenter.md, describing how Armbian board maintainers access the Datacenter hardware lab. It covers requesting access through the board-maintainers GitHub team, using the Netbird VPN, SSH access to boards as root, a reflashing warning, and an auto-updated boards table. mkdocs.yml is also updated with a new Datacenter access navigation entry under CONTRIBUTE.

File	Change Summary
docs/Contribute/Datacenter.md	New Datacenter access documentation page with access request, VPN, SSH, warning, and boards list sections
mkdocs.yml	Added the Datacenter access navigation entry

Estimated code review effort: 1 (Trivial) | ~5 minutes

Related issues: None specified.

Related PRs: None specified.

Suggested labels: documentation

Suggested reviewers: None specified.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the new Datacenter access documentation and its Netbird/board access focus.
Description check	✅ Passed	The description clearly matches the PR by describing the Datacenter access page, Netbird VPN, and board access details.
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 feat/datacenter-access-docs

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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/Contribute/Datacenter.md`:
- Around line 94-96: The Datacenter board description currently states that the
list is already kept up to date automatically, but this change only adds the
static snapshot/scaffold. Update the wording in the Datacenter docs to use
future/intent language such as “intended to be kept up to date automatically,”
or point to the actual refresh job if that exists, so the text matches the
current implementation.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

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

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 09084260-3266-4eb4-ab66-f730de05f663

📥 Commits

Reviewing files that changed from the base of the PR and between 2f67476 and 614f224.

⛔ Files ignored due to path filters (1)

• docs/images/dc-rack.png is excluded by !**/*.png

📒 Files selected for processing (2)

• docs/Contribute/Datacenter.md
• mkdocs.yml

[igorpecovnik]

@SuperKali Did I missed anything?

[SuperKali]

I give a look in the morning later, I just woke up now

[SuperKali]

@igorpecovnik Most of the information regarding Netbird is correct, but as you mentioned before, take screenshots from the forum and add them there—because users might not realize that to log in to Netbird, they need to click “Use Authentik” and then click the GitHub logo below it in Authentik. I’d also add that the board has its own FQDN: slug.test(1,2).armbian.lan, in case that’s of interest.