Add a selected calendar

curl --request POST \
  --url https://api.cal.com/v2/selected-calendars \
  --header 'Content-Type: application/json' \
  --data '{
  "integration": "<string>",
  "externalId": "<string>",
  "credentialId": 123,
  "delegationCredentialId": "<string>"
}'

{
  "status": "success",
  "data": {
    "userId": 123,
    "integration": "<string>",
    "externalId": "<string>",
    "credentialId": 123
  }
}