Docs: add a docs/ set mirroring Pithead (getting-started, configuration, operations, hardware, tuning, faq, integration) #25

Goal

RigForge ships only README.md + LICENSE. Mirror Pithead's docs/ set so the two read as one product (same structure, tone, and an index table). Pithead's set for reference: README (index), getting-started, hardware, configuration, dashboard, workers, architecture, operations, releasing, faq.

Proposed docs/ (miner-appropriate)

• docs/README.md — index table linking the pages (mirrors Pithead's docs index).
• docs/getting-started.md — fresh machine → tuned worker in one command: prerequisites, first run, the Linux reboot, verification.
• docs/hardware.md — worker CPU/RAM/HugePages requirements + the per-CPU tuning profiles (lift from README, expand).
• docs/configuration.md — every config key + default, minimal vs advanced, and the apply flow (ties to Two-tier config like Pithead: minimal config.json + config.advanced.example.json (every key + defaults) #23).
• docs/operations.md — full command reference (ties to Add a command surface + doctor (status/logs/up/down/restart/upgrade/help) #11), service management, logs, upgrade, doctor, and troubleshooting (MSR/Secure Boot, HugePages not applying, AVX2).
• docs/tuning.md — RigForge's analogue of Pithead's architecture.md: what the script actually does (deps, compile-from-source, HugePages 1G/2M, MSR, NUMA, cpupower governor, systemd service).
• docs/pithead-integration.md — the worker↔dashboard contract from Honor & document the Pithead worker-API contract (port 8080 · token = rig name · restricted=true) #24: discovery via :3333, API on :8080, token = rig name (or none), restricted: true, and the "custom token breaks the dashboard" caveat.
• docs/faq.md — common questions/issues (incl. "RigForge vs. doing it by hand", Secure Boot, etc.).
• Slim README.md to a quick-start that points at docs/.

Already tracked — don't duplicate

• SECURITY.md, CONTRIBUTING.md, issue/PR templates → Community-health files: SECURITY.md, CONTRIBUTING.md, issue/PR templates #10.
• VERSION, CHANGELOG.md, docs/releasing.md + release process → Release & versioning structure (VERSION + tags + CHANGELOG + process) #3.

Acceptance

• docs/ exists with the pages above, cross-linked from docs/README.md, matching Pithead's structure and tone.
• README.md links out to docs/ instead of holding everything.

Note

Several pages depend on features still in flight — configuration.md/apply on #23, operations.md on #11 — so they can be stubbed and filled as those land. Happy to split this into per-page issues if preferred.