[DOC] Add documentation for URI path filterning support for cluster/stats API.

[SwethaGuptha]

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.
With opensearch-project/OpenSearch#15938, the cluster/stats API will have filtering support that will allow the clients to fetch only specific metrics from cluster/stats instead of all metrics. This is similar to current support provided in _nodes/stats API. As mentioned in the original issue, the API will support two new URI paths:

/_cluster/stats/{metric}/nodes/{nodeId}
/_cluster/stats/{metric}/{index_metric}/nodes/{nodeId}

Valid Metrics:

os, process, jvm, fs, plugins, ingest, network_types, discovery_types, packaging_types, indices, _all

Valid Index Metrics:

shards, docs, store , field_data, query_cache, completion, segments, analysis, mappings, _all

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

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