Revert "Revert "list: print message with there's no task with description""

This reverts commit e065dcb.

Reintroducing this. Reverted unintentionally.

Author: andreynering

help.go

@@ -10,9 +10,10 @@ import (
 func (e *Executor) PrintTasksHelp() {
 	tasks := e.tasksWithDesc()
 	if len(tasks) == 0 {
+		e.outf("task: No tasks with description available")
 		return
 	}
-	e.outf("Available tasks for this project:")
+	e.outf("task: Available tasks for this project:")
 
 	// Format in tab-separated columns with a tab stop of 8.
 	w := tabwriter.NewWriter(e.Stdout, 0, 8, 0, '\t', 0)