Fix find_stucture format enum (#5705) (#5707)

* Fix find_structure format enum

* Run make spec-format-fix

(cherry picked from commit 93701e0)

Co-authored-by: Quentin Pradet <quentin.pradet@elastic.co>

Author: github-actions[bot]

specification/text_structure/find_structure/FindStructureRequest.ts

@@ -96,7 +96,7 @@ export interface Request<TJsonDocument> {
      * In this default scenario, all rows must have the same number of fields for a delimited format to be detected.
      * If the format is set to `delimited` and the delimiter is not set, however, the API tolerates up to 5% of rows that have a different number of columns than the first row.
      */
-    format?: string
+    format?: FindStructureFormat
     /**
      * If you have set `format` to `semi_structured_text`, you can specify a Grok pattern that is used to extract fields from every message in the text.
      * The name of the timestamp field in the Grok pattern must match what is specified in the `timestamp_field` parameter.
@@ -205,3 +205,10 @@ export interface Request<TJsonDocument> {
    * @codegen_name text_files */
   body: Array<TJsonDocument>
 }
+
+export enum FindStructureFormat {
+  ndjson,
+  xml,
+  delimited,
+  semi_structured_text
+}