Update Slovak language

Based on #10313 by @rmoravcik

Marlin/src/lcd/language/language_sk_utf8.h

 #define MSG_BABYSTEP_Z                      _UxGT("Babystep Z")
 #define MSG_ENDSTOP_ABORT                   _UxGT("Endstop zastavil")
 #define MSG_HEATING_FAILED_LCD              _UxGT("Chyba ohrevu")
+#define MSG_HEATING_FAILED_LCD_BED          _UxGT("Chyba ohrevu podl.")
 #define MSG_ERR_REDUNDANT_TEMP              _UxGT("REDUND. TEPLOTA")
 #define MSG_THERMAL_RUNAWAY                 _UxGT("TEPLOTNÝ SKOK")
 #define MSG_THERMAL_RUNAWAY_BED             _UxGT("TEPLOTNÝ SKOK PODL.")
 #define MSG_SHORT_MINUTE                    _UxGT("m")
 #define MSG_HEATING                         _UxGT("Ohrev...")
 #define MSG_HEATING_COMPLETE                _UxGT("Ohrev prebehol.")
+#define MSG_COOLING                         _UxGT("Ochladzovanie...")
+#define MSG_COOLING_COMPLETE                _UxGT("Ochladzovanie prebehlo.")
 #define MSG_BED_HEATING                     _UxGT("Ohrev podl.")
+#define MSG_BED_COOLING                     _UxGT("Ochladzovanie podl.")
 #define MSG_BED_DONE                        _UxGT("Podložka hotová.")
 #define MSG_DELTA_CALIBRATE                 _UxGT("Delta Kalibrácia")
 #define MSG_DELTA_CALIBRATE_X               _UxGT("Kalibrovať X")