ESQL: Update text formats documentation (#5054)

Spec docs update for the ESQL `format` parameter. Text formats result in missing metadata in the response body.

Main docs change: elastic/docs-content#2307

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/openapi/elasticsearch-serverless-openapi.json

@@ -58,7 +58,12 @@ export interface Request extends RequestBase {
      */
     drop_null_columns?: boolean
     /**
-     * A short version of the Accept header, for example `json` or `yaml`.
+     * A short version of the Accept header, e.g. json, yaml.
+     *
+     * `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.
+     * The query ID and running status are available in the `X-Elasticsearch-Async-Id` and `X-Elasticsearch-Async-Is-Running` HTTP headers of the response, respectively.
      */
     format?: EsqlFormat
   }

output/schema/schema.json

@@ -43,6 +43,8 @@ export interface Request extends RequestBase {
   query_parameters: {
     /**
      * A short version of the Accept header, e.g. json, yaml.
+     *
+     * `csv`, `tsv`, and `txt` formats will return results in a tabular format, excluding other metadata fields from the response.
      */
     format?: EsqlFormat
     /**