Retrieves a severity

curl --request GET \
  --url https://api.rootly.com/v1/severities/{id} \
  --header 'Authorization: Bearer <token>'

{
  "data": {
    "id": "25acb9a3-ee04-4f3d-80e6-f5cbcd9454e7",
    "type": "severities",
    "attributes": {
      "name": "nm3yz",
      "slug": "nm3yz",
      "description": "Maiores perferendis deleniti et.",
      "severity": "medium",
      "color": "#E58A1F",
      "position": 1,
      "notify_emails": [],
      "slack_channels": [],
      "slack_aliases": [],
      "created_at": "2025-08-11T20:46:42.017-07:00",
      "updated_at": "2025-08-11T20:46:42.017-07:00"
    }
  }
}