Feat: update jp docs guideline

docs.json

@@ -894,7 +894,7 @@
         ]
       },
       {
-        "language": "ja",
+        "language": "jp",
         "href": "/ja-jp/introduction",
         "tabs": [
           {
@@ -1345,6 +1345,10 @@
                 ]
               }
             ]
+          },
+          {
+            "tab": "API リファレンス",
+            "openapi": "https://assets-docs.dify.ai/2025/03/d497c10fe2c248a01ac93f6cfdf210b1.json"
           }
         ]
       }