[DOC] Flat Object

[macohen]

What do you want to do?

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

Tell us about your request. Provide a summary of the request and all versions that are affected.
We are targeting a 2.6.0 release for a feature to store full JSON objects without analyzing them. Today, by default, a JSON is stored and analyzed. In many cases, users do not need or want to index all fields in the object. This new feature will allow them to specify a document in mapping so they can use "dot" notation to access data in an object, but it will not be indexed.

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.
opensearch-project/OpenSearch#1018

@mingshl

[hdhalter]

According to the scorecard, this is targeted for 2.7. Changing the label to 2.7.