add availability to oversample value of 0 (#131707)

Author: shainaraskas

docs/reference/elasticsearch/mapping-reference/dense-vector.md

@@ -295,7 +295,10 @@ $$$dense-vector-index-options$$$
 : (Optional, object) An optional section that configures automatic vector rescoring on knn queries for the given field. Only applicable to quantized index types.
 :::::{dropdown} Properties of rescore_vector
 `oversample`
-: (required, float) The amount to oversample the search results by. This value should be greater than `1.0` and less than `10.0` or exactly `0` to indicate no oversampling & rescoring should occur. The higher the value, the more vectors will be gathered and rescored with the raw values per shard.
+: (required, float) The amount to oversample the search results by. This value should be one of the following: 
+ * Greater than `1.0` and less than `10.0` 
+ * Exactly `0` to indicate no oversampling and rescoring should occur {applies_to}`stack: ga 9.1`
+ : The higher the value, the more vectors will be gathered and rescored with the raw values per shard.
  : In case a knn query specifies a `rescore_vector` parameter, the query `rescore_vector` parameter will be used instead.
  : See [oversampling and rescoring quantized vectors](docs-content://solutions/search/vector/knn.md#dense-vector-knn-search-rescoring) for details.
 :::::

docs/reference/query-languages/query-dsl/query-dsl-knn-query.md

@@ -113,7 +113,9 @@ Rescoring only makes sense for quantized vectors; when [quantization](/reference
  * Retrieve `num_candidates` candidates per shard.
  * From these candidates, the top `k * oversample` candidates per shard will be rescored using the original vectors.
  * The top `k` rescored candidates will be returned.
- Must be >= 1f to indicate oversample factor, or exactly `0` to indicate that no oversampling and rescoring should occur.
+ Must be one of the following values: 
+ * \>= 1f to indicate the oversample factor
+ * Exactly `0` to indicate that no oversampling and rescoring should occur. {applies_to}`stack: ga 9.1`
 
 
 See [oversampling and rescoring quantized vectors](docs-content://solutions/search/vector/knn.md#dense-vector-knn-search-rescoring) for details.