curl --request POST \
  --url https://api.voltview.co.uk/v1/createUserSiteAssignments \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "userId": "<string>",
  "siteId": "<string>"
}
'

{
  "success": true,
  "message": "<string>"
}