Adds external link to the Synonyms API (#4756) (#4770)

* Adds external link to the Synonyms API

* Formatting fix

* Code style fix

(cherry picked from commit 644201b)

Author: kosabogi

output/openapi/elasticsearch-openapi.json

@@ -871,6 +871,7 @@ start-trial,https://www.elastic.co/docs/api/doc/elasticsearch/v9/operation/opera
 stop-dfanalytics,https://www.elastic.co/docs/api/doc/elasticsearch/v9/operation/operation-ml-stop-data-frame-analytics,https://www.elastic.co/guide/en/elasticsearch/reference/8.18/stop-dfanalytics.html
 stop-trained-model-deployment,https://www.elastic.co/docs/api/doc/elasticsearch/v9/operation/operation-ml-stop-trained-model-deployment,https://www.elastic.co/guide/en/elasticsearch/reference/8.18/stop-trained-model-deployment.html
 stop-transform,https://www.elastic.co/docs/api/doc/elasticsearch/v9/operation/operation-transform-stop-transform,https://www.elastic.co/guide/en/elasticsearch/reference/8.18/stop-transform.html
+synonym-api-examples,https://www.elastic.co/docs/solutions/search/full-text/create-update-synonyms-api-example,https://www.elastic.co/guide/en/elasticsearch/reference/8.18/put-synonyms-set.html
 stored-fields,https://www.elastic.co/docs/reference/elasticsearch/rest-apis/retrieve-selected-fields#stored-fields,
 synonym-rule-create,https://www.elastic.co/docs/api/doc/elasticsearch/v9/operation/operation-synonyms-put-synonym-rule,https://www.elastic.co/guide/en/elasticsearch/reference/8.18/put-synonym-rule.html
 synonym-rule-delete,https://www.elastic.co/docs/api/doc/elasticsearch/v9/operation/operation-synonyms-delete-synonym-rule,https://www.elastic.co/guide/en/elasticsearch/reference/8.18/delete-synonym-rule.html

output/openapi/elasticsearch-serverless-openapi.json

@@ -27,11 +27,14 @@ import { SynonymRule } from '../_types/SynonymRule'
  *
  * When an existing synonyms set is updated, the search analyzers that use the synonyms set are reloaded automatically for all indices.
  * This is equivalent to invoking the reload search analyzers API for all indices that use the synonyms set.
+ *
+ * For practical examples of how to create or update a synonyms set, refer to the External documentation.
  * @rest_spec_name synonyms.put_synonym
  * @availability stack since=8.10.0 stability=stable
  * @availability serverless stability=stable visibility=public
  * @cluster_privileges manage_search_synonyms
  * @doc_id synonym-set-create
+ * @ext_doc_id synonym-api-examples
  */
 export interface Request extends RequestBase {
   urls: [