add note to cron generated with the currrent user

README.md

@@ -23,12 +23,14 @@ This will create an initial `config/schedule.rb` file for you (as long as the co
 
 ### The `whenever` command
 
+The `whenever` command will simply show you your `schedule.rb` file converted to cron syntax. It does not read or write your crontab file.
+
 ```sh
 $ cd /apps/my-great-project
 $ bundle exec whenever
 ```
 
-This will simply show you your `schedule.rb` file converted to cron syntax. It does not read or write your crontab file; you'll need to do this in order for your jobs to execute:
+To write your crontab file for your jobs, execute this command:
 
 ```sh
 $ whenever --update-crontab
@@ -41,6 +43,8 @@ $ whenever --load-file config/my_schedule.rb # set the schedule file
 $ whenever --crontab-command 'sudo crontab' # override the crontab command
 ```
 
+> Note: If you run the whenever --update-crontab without passing the --user attribute, cron will be generated by the current user. This mean tasks that needs other user permission will fail.
+
 You can list installed cron jobs using `crontab -l`.
 
 Run `whenever --help` for a complete list of options for selecting the schedule to use, setting variables in the schedule, etc.