Update doc/usage.md

doc/usage.md

@@ -142,7 +142,7 @@ To configure a predefined formatter class, just set it as the handler's field:
 // the default date format is "Y-m-d H:i:s"
 $dateFormat = "Y n j, g:i a";
 // the default output format is "[%datetime%] %channel%.%level_name%: %message% %context% %extra%\n"
-$output = "%datetime% > %level_name% > %message% %context% %extra%\n"
+$output = "%datetime% > %level_name% > %message% %context% %extra%\n";
 // finally, create a formatter
 $formatter = new LineFormatter($output, $dateFormat);