fix rerank issue when doing economy search (#1978)

Co-authored-by: jyong <jyong@dify.ai>

api/core/index/keyword_table_index/keyword_table_index.py

@@ -136,6 +136,7 @@ class KeywordTableIndex(BaseIndex):
                     page_content=segment.content,
                     metadata={
                         "doc_id": chunk_index,
+                        "doc_hash": segment.index_node_hash,
                         "document_id": segment.document_id,
                         "dataset_id": segment.dataset_id,
                     }