add sentence

resource/locales/en_US/admin/admin.json

@@ -314,6 +314,7 @@
       "paste_growi_url": "Since a modal is displayed, enter the following URL in <b>GROWI URL</b>.",
       "enter_access_token_for_growi_and_proxy": "Enter <b>Access Token for GROWI</b> and <b>Access Token for Proxy</b>",
       "set_proxy_url_on_growi": "Set Proxy URL on GROWI",
+      "copy_proxy_url": "1. When the above step ② are completed successfully, the Proxy URL will be displayed in the Slack Channel you selected in the modal, so copy it.",
       "enter_proxy_url_and_update": "1. Enter and update the Proxy URL that you copied in step ③ in the <b>Proxy URL</b>  of the <b>Custom bot with proxy integration</b> on this page.",
       "dont_need_update": "※If the value is already in there, there is no need to update it.",
       "select_install_your_app": "Select \"Install your app\".",

resource/locales/ja_JP/admin/admin.json

@@ -311,6 +311,7 @@
       "paste_growi_url": "モーダルが表示されるので、<b>GROWI URL</b> には下記のURLを入力します。",
       "enter_access_token_for_growi_and_proxy": "上記で発行した<b>Access Token for GROWI</b> と <b>Access Token for Proxy</b>を入れる",
       "set_proxy_url_on_growi": "ProxyのURLをGROWIに登録する",
+      "copy_proxy_url": "1. ②が正常に完了すると、モーダル内で選択したSlack ChannelにProxy URLが表示されるので、コピーします。",
       "enter_proxy_url_and_update": "1. 連携手順③でコピーしたProxy URLを、このページの<b>Custom bot with proxy 連携</b>の<b>Proxy URL</b>に入力、更新します。",
       "dont_need_update": "※既に値が入っている場合は更新する必要はありません",
       "select_install_your_app": "Install your app をクリックします。",

resource/locales/zh_CN/admin/admin.json

@@ -321,6 +321,7 @@
       "paste_growi_url": "由于显示了模式，请在 <b>GROWI URL</b> 中输入以下URL",
       "enter_access_token_for_growi_and_proxy": "插入上面发出的 <b>Access Token for GROWI</b> 和 <b>Access Token for Proxy</b>。",
       "set_proxy_url_on_growi": "向GROWI注册Proxy的URL",
+      "copy_proxy_url": "1. 当上述步骤②成功完成后，Proxy URL将显示在你在模版中选择的Slack频道中，所以请复制它。",
       "enter_proxy_url_and_update": "1. 输入并更新你在步骤③中复制的ProxyURL到本页的<b>Custom bot with proxy 一体化</b>的<b>ProxyURL</b>。",
       "dont_need_update": "※如果值已经在里面了，就不需要再更新。",
       "select_install_your_app": "选择 \"Install your app\"。",