add alert to notify deplicated

packages/app/resource/locales/en_US/admin/admin.json

@@ -349,6 +349,9 @@
       "custom_bot_with_proxy_setting": "https://docs.growi.org/en/admin-guide/management-cookbook/slack-integration/custom-bot-with-proxy-settings.html"
     }
   },
+  "slack_integration_legacy": {
+    "alert_deplicated": "This 'Legacy Slack Integration' is outdated and will be discontinued in the future. To use new settings: "
+  },
   "user_management": {
     "invite_users": "Temporarily issue a new user",
     "click_twice_same_checkbox": "You should check at least one checkbox.",

packages/app/resource/locales/ja_JP/admin/admin.json

@@ -348,6 +348,9 @@
       "custom_bot_with_proxy_setting": "https://docs.growi.org/ja/admin-guide/management-cookbook/slack-integration/custom-bot-with-proxy-settings.html"
     }
   },
+  "slack_integration_legacy": {
+    "alert_deplicated": "この 'Slack連携 (レガシー)' は将来廃止されます。新しいSlack連携機能はこちら: "
+  },
   "user_management": {
     "invite_users": "新規ユーザーの仮発行",
     "click_twice_same_checkbox": "少なくとも一つはチェックしてください。",

packages/app/resource/locales/zh_CN/admin/admin.json

@@ -358,6 +358,9 @@
       "custom_bot_with_proxy_setting": "https://docs.growi.org/en/admin-guide/management-cookbook/slack-integration/custom-bot-with-proxy-settings.html"
     }
   },
+  "slack_integration_legacy": {
+    "alert_deplicated": "这个 '旧版Slack一体化' 已经过时了，将来会停止使用。要使用新功能: "
+  },
   "user_management": {
     "invite_users": "临时发布新用户",
     "click_twice_same_checkbox": "您应该至少选中一个复选框。",

packages/app/src/components/Admin/LegacySlackIntegration/LegacySlackIntegration.jsx

@@ -1,5 +1,6 @@
 import React, { useMemo, useState } from 'react';
 import PropTypes from 'prop-types';
+import { useTranslation } from 'react-i18next';
 
 import loggerFactory from '~/utils/logger';
 
@@ -16,6 +17,7 @@ const logger = loggerFactory('growi:NotificationSetting');
 
 let retrieveErrors = null;
 function LegacySlackIntegration(props) {
+  const { t } = useTranslation();
   const { adminSlackIntegrationLegacyContainer } = props;
 
   if (adminSlackIntegrationLegacyContainer.state.webhookUrl === adminSlackIntegrationLegacyContainer.dummyWebhookUrl) {
@@ -38,7 +40,15 @@ function LegacySlackIntegration(props) {
   }
 
   return (
-    <SlackConfiguration />
+    <>
+      <div className="alert alert-warning">
+        <i className="icon-info icon-fw"></i>
+        {t('admin:slack_integration_legacy.alert_deplicated')}
+        <strong><a href="/admin/slack-integration">{t('slack_integration')}</a> <i className="icon-login"></i></strong>
+      </div>
+
+      <SlackConfiguration />
+    </>
   );
 }