Added missing POST method to create.json REST spec

Relates to #20924

rest-api-spec/src/main/resources/rest-api-spec/api/create.json

@@ -1,7 +1,7 @@
 {
   "create": {
     "documentation": "http://www.elastic.co/guide/en/elasticsearch/reference/master/docs-index_.html",
-    "methods": ["PUT"],
+    "methods": ["PUT","POST"],
     "url": {
       "path": "/{index}/{type}/{id}/_create",
       "paths": ["/{index}/{type}/{id}/_create"],