[DOC] No documentation present on how to use rescore using Opensearch

[navneet1v]

What do you want to do?

• Request a change to existing documentation
• Add new documentation
• Report a technical problem with the documentation
• Other

Tell us about your request. Provide a summary of the request.
Opensearch since the fork supports doing rescore of the results using rescore queries. But in the current documentation there is no documentation present for doing the rescore. Creating this GH issue so that rescore docs can be added in Opensearch documentation.

Refer below example:

POST my-index/_search
{
   "query" : {
      "match" : {
         "message" : {
            "operator" : "and",
            "query" : "Opensearch supports rescore"
         }
      }
   },
   "rescore" : {
      "window_size" : 50,
      "query" : {
         "rescore_query" : {
            "match_phrase" : {
               "message" : {
                  "query" : "rescore",
                  "slop" : 2
               }
            }
         },
         "query_weight" : 0.7,
         "rescore_query_weight" : 1.2
      }
   }
}

*Version: List the OpenSearch version to which this issue applies, e.g. 2.14, 2.12--2.14, or all.
all

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.

[navneet1v]

@Naarcha-AWS any reason for assigning this to me, as I don't own this feature? 😅