Create escalation policy

POST /api/v1/alerts/escalations

{
  "name": "Primary operations",
  "steps": [
    {
      "targets": [
        {
          "kind": "schedule",
          "schedule_id": "<schedule-id>",
          "channel_ids": ["<channel-id>"]
        }
      ],
      "ack_timeout_secs": 300,
      "min_severity": "warning"
    }
  ],
  "repeat": true,
  "max_loops": 2
}