Update async docs around headers

Author: ivancea

output/openapi/elasticsearch-openapi.json

@@ -43,7 +43,17 @@ export class EsqlResult {
 }
 
 export class AsyncEsqlResult extends EsqlResult {
+  /**
+   * The ID of the async query, to be used in subsequent requests to check the status or retrieve results.
+   *
+   * Also available in the `X-Elasticsearch-Async-Id` HTTP header.
+   */
   id?: string
+  /**
+   * Indicates whether the async query is still running or has completed.
+   *
+   * Also available in the `X-Elasticsearch-Async-Is-Running` HTTP header.
+   */
   is_running: boolean
 }
 

output/schema/schema.json

@@ -63,6 +63,7 @@ export interface Request extends RequestBase {
      * `csv`, `tsv`, and `txt` formats will return results in a tabular format, excluding other metadata fields from the response.
      *
      * For async requests, nothing will be returned if the async query doesn't finish within the timeout.
+     * You should then take the query ID and status from the `X-Elasticsearch-Async-Id` and `X-Elasticsearch-Async-Is-Running` HTTP headers, respectively.
      */
     format?: EsqlFormat
   }