cleanup-submission option

System-configuration.md

@@ -58,6 +58,9 @@ of the particular worker instance.
 - **max-output-length** -- used for `tasks.{task}.sandbox.output` option, defined
   in bytes, applied to both stdout and stderr and is not divided, both will get
   this value
+- **cleanup-submission** -- if set to true, then files produced during evaluation
+  of submission will be deleted at the end, extra caution is advised because this
+  setup can cause extensive disk usage
 
 ### Example config file