Adding new cluster search setting docs (opensearch-project#8180)

* Adding new cluster search setting docs

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

* Update _install-and-configure/configuring-opensearch/search-settings.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>
Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

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Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>
Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>
Signed-off-by: Eric Pugh <epugh@opensourceconnections.com>

_install-and-configure/configuring-opensearch/search-settings.md

@@ -39,6 +39,8 @@ OpenSearch supports the following search settings:
 
 - `search.dynamic_pruning.cardinality_aggregation.max_allowed_cardinality` (Dynamic, integer): Determines the threshold for applying dynamic pruning in cardinality aggregation. If a field’s cardinality exceeds this threshold, the aggregation reverts to the default method. This is an experimental feature and may change or be removed in future versions.
 
+- `search.keyword_index_or_doc_values_enabled` (Dynamic, Boolean): Determines whether to use the index or doc values when running `multi_term` queries on `keyword` fields. Default value is `false`.
+
 ## Point in Time settings
 
 For information about PIT settings, see [PIT settings]({{site.url}}{{site.baseurl}}/search-plugins/point-in-time-api/#pit-settings).