fix(api): fix en/api-reference/openapi_knowledge.json (#657)

* fix(api): change reranking_mode to reranking_model in openapi_knowledge.json

* add reranking mode field

* update reranking mode description;  standardize rerank model terminology

---------

Co-authored-by: Zhiqiang Yang <58433399+yangzq50@users.noreply.github.com>
Co-authored-by: Riskey <riskey47@dify.ai>

ja/api-reference/openapi_knowledge.json

@@ -1770,6 +1770,15 @@
             "description": "検索結果を改善するためのリランキングモデルを有効にするかどうか。"
           },
           "reranking_mode": {
+            "type": "string",
+            "description": "リランキングモード。",
+            "default": "reranking_model",
+            "enum": [
+              "reranking_model",
+              "weighted_score"
+            ]
+          },
+          "reranking_model": {
             "type": "object",
             "description": "リランキングモデルの設定。",
             "properties": {