adjust message

packages/slackbot-proxy/src/controllers/growi-to-slack.ts

@@ -201,7 +201,7 @@ export class GrowiToSlackCtrl {
       return res.status(400).send({ message: `failed to send to slack. err: ${err.message}` });
     }
 
-    logger.debug('postMessage is success');
+    logger.debug('send to slack is success');
 
     // required to return ok for apiCall
     return res.send({ ok: true });