[DOC] Add examples of updating model interface

[ylwu-amzn]

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We have document for update model https://opensearch.org/docs/latest/ml-commons-plugin/api/model-apis/update-model/.
With OpenSearch Flow released in 2.19, we need to build some example of how to update model interface in this doc.

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

2.19 and above

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