[DOC] knn-index space-type parameter docs don't match functionality

[SohaibKatariwala]

What do you want to do?
To create a knn-index I'm trying to specify space-type inside the top level of the mapping like in this example from the docs:
PUT /test-index { "settings": { "index": { "knn": true } }, "mappings": { "properties": { "my_vector1": { "type": "knn_vector", "dimension": 3, "space_type": "l2", "method": { "name": "hnsw", "engine": "lucene", "parameters": { "ef_construction": 128, "m": 24 } } } } } }

This fails with the error: "unknown parameter [space_type] on mapper [my_vector1] of type [knn_vector]". (on v2.15 and v2.13 at least)

This documentation says "Note: This value can also be specified at the top level of the mapping."

Either this is a bug in OpenSearch or the documentation is wrong.

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*Version: List the OpenSearch version to which this issue applies, e.g. 2.14, 2.12--2.14, or all.
v2.13 and v2.15

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