Monitor investors

curl --request POST \
  --url https://api.registercheck.de/api/v1/watchlist/verify_investor \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --data '{
  "investors_to_verify": [
    {
      "name": "<string>",
      "is_company": true,
      "birth_date": "<string>",
      "register_number": "<string>"
    }
  ],
  "frequency": {}
}'

{
  "message": "<string>",
  "watchlist_id": "<string>"
}