docs: document MikroTik ACME certificates

[jmgilman]

Summary

• document the CCR2004 and CRS309 WebFig HTTPS names and addresses
• record the RouterOS ACME command used on current device versions
• capture the HTTP-01 source-address restrictions and chain import behavior observed during setup

Validation

• ran npm ci
• ran npm run build
• ran npm run typecheck

Notes

• wt was unavailable locally, so this branch was created with plain git worktree to preserve worktree isolation