curl --request POST \
  --url https://api.letpiper.com/v1/orgs/{org_id}/knowledge/documents \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: multipart/form-data' \
  --form collectionId=3c90c3cc-0d44-4b50-8888-8dd25736052a \
  --form 'files=<string>' \
  --form 'language=<string>' \
  --form files.items='@example-file'

{
  "requestId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "collectionId": "<string>",
  "totalFiles": 123,
  "successes": 123,
  "failures": 123,
  "results": [
    {
      "filename": "<string>",
      "mimeType": "<string>",
      "bytesIngested": 123,
      "status": "pending",
      "documentId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "error": "<string>",
      "relativePath": "<string>",
      "isDuplicate": false,
      "existingDocumentId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "title": "<string>",
      "language": "<string>"
    }
  ]
}