fix(debian): preserve vector.yaml as a conffile + move examples to docs folder

[koen-serry]

Summary

Vector configuration

How did you test this PR?

Change Type

• Bug fix
• New feature
• Dependencies
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

Notes

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[github-actions]

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[koen-serry]

I have no clue what that CLA Assistant is

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Avoid conffile prompts on upgrades

For Debian users who installed a version where /etc/vector/vector.yaml was not package-owned and then created that file themselves, adding the same path as a new dpkg conffile makes dpkg -i stop at the “File on system created by you” conffile prompt; without explicit --force-confold/confnew options, unattended apt/dpkg upgrades fail before the package is configured. The new verify path only reinstalls this same package, so it misses the transition from an unowned user config to a packaged conffile; please add a maintainer-script transition or another approach that preserves the existing file without prompting.

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[koen-serry]

I have read the CLA Document and I hereby sign the CLA