Clarify environment_name for logs

[ci skip]

guides/source/debugging_rails_applications.md

@@ -123,7 +123,7 @@ config.logger = Logger.new(STDOUT)
 config.logger = Log4r::Logger.new("Application Log")
 ```
 
-TIP: By default, each log is created under `Rails.root/log/` and the log file name is `environment_name.log`.
+TIP: By default, each log is created under `Rails.root/log/` and the log file name is `environment_name.log`. example `production.log`, `development.log` etc.
 
 ### Log Levels