add a few example requests for endpoints that do not use bodies

Author: miguelgrinberg

output/openapi/elasticsearch-openapi.json

@@ -0,0 +1 @@
+method_request: HEAD my-index-000001/_doc/0

output/openapi/elasticsearch-serverless-openapi.json

@@ -0,0 +1 @@
+method_request: POST /my-index-00001/_close

output/schema/schema.json

@@ -0,0 +1 @@
+method_request: GET /_data_stream/my-index-000001/_stats