Add batch inference API

[Zhangxunmt]

Description

Add doc for Batch Inference as a new API under the Ml-Commons/Model-API.

Issues Resolved

Closes https://github.com/opensearch-project/documentation-website/issues/7848

Version

List the OpenSearch version to which this PR applies, e.g. 2.14, 2.12--2.14, or all.

Frontend features

If you're submitting documentation for an OpenSearch Dashboards feature, add a video that shows how a user will interact with the UI step by step. A voiceover is optional.

Checklist

• [ ] By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and subject to the Developers Certificate of Origin. For more information on following Developer Certificate of Origin and signing off your commits, please check here.