Update MMU error texts

as per https://github.com/prusa3d/Prusa-Error-Codes/pull/71

Firmware/mmu2/errors_list.h

@@ -218,7 +218,7 @@ static const char MSG_DESC_FSENSOR_DIDNT_GO_OFF[] PROGMEM_I1 = ISTR("Filament se
 static const char MSG_DESC_PULLEY_STALLED[] PROGMEM_I1 = ISTR("Pulley motor stalled. Ensure the pulley can move and check the wiring."); ////MSG_DESC_PULLEY_STALLED c=20 r=8
 static const char MSG_DESC_FSENSOR_TOO_EARLY[] PROGMEM_I1 = ISTR("Filament sensor triggered too early while loading to extruder. Check there isn't anything stuck in PTFE tube. Check that sensor reads properly."); ////MSG_DESC_FSENSOR_TOO_EARLY c=20 r=8
 static const char MSG_DESC_INSPECT_FINDA[] PROGMEM_I1 = ISTR("Selector can't move due to FINDA detecting a filament. Make sure no filament is in selector and FINDA works properly."); ////MSG_DESC_INSPECT_FINDA c=20 r=8
-static const char MSG_DESC_LOAD_TO_EXTRUDER_FAILED[] PROGMEM_I1 = ISTR("@@TODO - load to extruder failed."); ////MSG_DESC_LOAD_TO_EXTRUDER_FAILED c=20 r=8
+static const char MSG_DESC_LOAD_TO_EXTRUDER_FAILED[] PROGMEM_I1 = ISTR("Loading to extruder failed. Inspect the filament tip shape. Refine the sensor calibration, if needed."); ////MSG_DESC_LOAD_TO_EXTRUDER_FAILED c=20 r=8
 static const char MSG_DESC_SELECTOR_CANNOT_HOME[] PROGMEM_I1 = ISTR("The Selector cannot home properly. Check for anything blocking its movement."); ////MSG_DESC_SELECTOR_CANNOT_HOME c=20 r=8
 static const char MSG_DESC_CANNOT_MOVE[] PROGMEM_I1 = ISTR("Can't move Selector or Idler."); /////MSG_DESC_CANNOT_MOVE c=20 r=4
 //static const char MSG_DESC_SELECTOR_CANNOT_MOVE[] PROGMEM_I1 = ISTR("The Selector cannot move. Check for anything blocking its movement. Check the wiring is correct.");
@@ -250,7 +250,7 @@ static const char MSG_DESC_INVALID_TOOL[] PROGMEM_I1 = ISTR("Requested filament
 static const char MSG_DESC_QUEUE_FULL[] PROGMEM_I1 = ISTR("MMU Firmware internal error, please reset the MMU."); ////MSG_DESC_QUEUE_FULL c=20 r=8
 static const char MSG_DESC_FW_UPDATE_NEEDED[] PROGMEM_I1 = ISTR("The MMU unit reports its FW version incompatible with the printer's firmware. Make sure the MMU firmware is up to date."); ////MSG_DESC_FW_UPDATE_NEEDED c=20 r=9
 static const char MSG_DESC_FW_RUNTIME_ERROR[] PROGMEM_I1 = ISTR("Internal runtime error. Try resetting the MMU unit or updating the firmware. If the issue persists, contact support."); ////MSG_DESC_FW_RUNTIME_ERROR c=20 r=11
-static const char MSG_DESC_UNLOAD_MANUALLY[] PROGMEM_I1 = ISTR("Unexpected FINDA reading. Ensure no filament is under FINDA and the selector is free. Check FINDA connection."); ////MSG_DESC_UNLOAD_MANUALLY c=20 r=8
+static const char MSG_DESC_UNLOAD_MANUALLY[] PROGMEM_I1 = ISTR("Filament detected unexpectedly. Ensure no filament is loaded. Check the sensors and wiring."); ////MSG_DESC_UNLOAD_MANUALLY c=20 r=8
 
 static const char * const errorDescs[] PROGMEM = {
     _R(MSG_DESC_FINDA_DIDNT_TRIGGER),