add debug:error_position (#655)

pages/Configuring/Variables.md

@@ -435,6 +435,7 @@ Only for developers.
 | watchdog_timeout | sets the timeout in seconds for watchdog to abort processing of a signal of the main thread. Set to 0 to disable. | int | 5 |
 | disable_scale_checks | disables verification of the scale factors. Will result in pixel alignment and rounding errors. | bool | false |
 | error_limit | limits the number of displayed config file parsing errors. | int | 5 | 
+| error_position | sets the position of the error bar. top - 0, bottom - 1 | int | 0 |
 | colored_stdout_logs | enables colors in the stdout logs. | bool | true |
 
 ### More