send a message when the new page is successfully created

src/server/service/slackbot.js

@@ -267,6 +267,12 @@ class SlackBotService extends S2sMessageHandlable {
           ],
         },
       });
+
+      await client.chat.postEphemeral({
+        channel: body.channel_id,
+        user: body.user_id,
+        text: 'Successfully created a new page.',
+      });
     }
     catch (err) {
       logger.error('Failed to create a page.');