Consumer-facing documentation for project suspension

[scotwells]

Consumer-facing documentation explaining what suspension means for a customer's project.

Acceptance criteria

• What's paused vs. retained when a project is suspended.
• What to expect on reinstatement (resume behavior + latency).
• How to appeal / self-remediate (billing vs. abuse).
• Compute-specific behavior (with input from Handle project suspension in the compute service (non-destructive pause/resume) compute#182).

Dependencies: platform primitive; behavior finalized; input from compute#182.

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Part of the Project Suspension & Lifecycle Controls enhancement (datum-cloud/enhancements#800). Rendered proposal: https://github.com/datum-cloud/enhancements/blob/enhancement/project-suspension/enhancements/platform/project-suspension/README.md