Add rescorer retriever to the retrievers overview

solutions/search/retrievers-overview.md

@@ -29,6 +29,7 @@ Retrievers come in various types, each tailored for different search operations.
 * [**Standard Retriever**](elasticsearch://reference/elasticsearch/rest-apis/retrievers.md#standard-retriever). Returns top documents from a traditional [query](/explore-analyze/query-filter/languages/querydsl.md). Mimics a traditional query but in the context of a retriever framework. This ensures backward compatibility as existing `_search` requests remain supported. That way you can transition to the new abstraction at your own pace without mixing syntaxes.
 * [**kNN Retriever**](elasticsearch://reference/elasticsearch/rest-apis/retrievers.md#knn-retriever). Returns top documents from a [knn search](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-search#search-api-knn), in the context of a retriever framework.
 * [**Linear Retriever**](elasticsearch://reference/elasticsearch/rest-apis/retrievers.md#linear-retriever). Combines the top results from multiple sub-retrievers using a weighted sum of their scores. Allows to specify different weights for each retriever, as well as independently normalize the scores from each result set.
+* [**Rescorer retriever**](elasticsearch://reference/elasticsearch/rest-apis/retrievers.md#rescorer-retriever). Re-scores the results produced by its child retriever. Replaces the functionality of the [query rescorer](elasticsearch://reference/elasticsearch/rest-apis/filter-search-results.md#rescore).
 * [**RRF Retriever**](elasticsearch://reference/elasticsearch/rest-apis/retrievers.md#rrf-retriever). Combines and ranks multiple first-stage retrievers using the reciprocal rank fusion (RRF) algorithm. Allows you to combine multiple result sets with different relevance indicators into a single result set. An RRF retriever is a **compound retriever**, where its `filter` element is propagated to its sub retrievers.
 * [**Rule Retriever**](elasticsearch://reference/elasticsearch/rest-apis/retrievers.md#rule-retriever). Applies [query rules](elasticsearch://reference/elasticsearch/rest-apis/searching-with-query-rules.md#query-rules) to the query before returning results.
 * [**Text Similarity Re-ranker Retriever**](elasticsearch://reference/elasticsearch/rest-apis/retrievers.md#text-similarity-reranker-retriever).