apply translation

resource/locales/en_US/admin/admin.json

@@ -253,6 +253,7 @@
     "delete": "Delete"
   },
   "slack_integration": {
+    "use_env_var_if_empty": "If the value in the database is empty, the value of the environment variable <cod>{{variable}}</code> is used.",
     "access_token_settings": {
       "discard": "Discard",
       "generate": "Generate"

resource/locales/ja_JP/admin/admin.json

@@ -251,6 +251,7 @@
     "Directory_hierarchy_tag": "ディレクトリ階層タグ"
   },
   "slack_integration": {
+    "use_env_var_if_empty": "データベース側の値が空の場合、環境変数 <code>{{variable}}</code> の値を利用します",
     "access_token_settings": {
       "discard": "破棄",
       "generate": "発行"

resource/locales/zh_CN/admin/admin.json

@@ -261,6 +261,7 @@
 		"delete": "删除"
   },
   "slack_integration": {
+    "use_env_var_if_empty": "如果数据库中的值为空，则环境变量的值 <cod>{{variable}}</code> 启用。",
     "access_token_settings": {
       "discard": "丢弃",
       "generate": "生成"