curl --request POST \
  --url https://api.keebai.com/v1/messages/document \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "to": "+5491155555555",
  "phone_number_id": "100000000000001",
  "link": "<string>",
  "media_id": "<string>",
  "filename": "<string>",
  "caption": "<string>",
  "meta_data": {}
}
'

{
  "message_id": "<string>",
  "status": "sent",
  "sent_at": "<string>"
}