This API endpoint is used to add subscribers to a segment. The request method of this call needs to be "POST".
The segment id of the segment is passed in the URL and the list of subscribers to be added in the segment is passed in JSON format as a POST parameter in the API call.
Status: To denote whether the request succeeded or not. Values can be 'success' or 'failure'.
Message: Present in case of failure. Used to denote reason of failure.