clarify Error logs for Custom Commands

Author: MariadeAnton

user/deployment/heroku.md

@@ -97,7 +97,7 @@ Custom Heroku commands do not affect the Travis CI build status or trigger Travi
 
 Use an addon such as [Papertrail](https://elements.heroku.com/addons/papertrail){: data-proofer-ignore=""} or [Logentries](https://elements.heroku.com/addons/logentries){: data-proofer-ignore=""} to get notifications for `rake db:migrate` or other commands.
 
-These add-ons have email notification systems that can be triggered when certain string matches occur in your logs. For example you could trigger an e-mail notification if the log contains "this and all later migrations canceled".  
+These add-ons have email notification systems that can be triggered when certain string matches occur in your Heroku logs. For example you could trigger an e-mail notification if the log contains "this and all later migrations canceled".  
 
 ### Restarting Applications