Update README.md

Setters info updated

README.md

@@ -69,18 +69,20 @@ void mgos_mel_ac_get_params(struct mgos_mel_ac *mel, struct mgos_mel_ac_params *
 To write params to HVAC:
 
 ```c
-void mgos_mel_ac_set_power(struct mgos_mel_ac *mel, enum mgos_mel_ac_param_power power);
-void mgos_mel_ac_set_mode(struct mgos_mel_ac *mel, enum mgos_mel_ac_param_mode mode);
-void mgos_mel_ac_set_setpoint(struct mgos_mel_ac *mel, float setpoint);
-void mgos_mel_ac_set_ext_temp(struct mgos_mel_ac *mel, float temp);
-void mgos_mel_ac_set_fan(struct mgos_mel_ac *mel, enum mgos_mel_ac_param_fan fan);
-void mgos_mel_ac_set_vane_vert(struct mgos_mel_ac *mel,
+bool mgos_mel_ac_set_power(struct mgos_mel_ac *mel, enum mgos_mel_ac_param_power power);
+bool mgos_mel_ac_set_mode(struct mgos_mel_ac *mel, enum mgos_mel_ac_param_mode mode);
+bool mgos_mel_ac_set_setpoint(struct mgos_mel_ac *mel, float setpoint);
+bool mgos_mel_ac_set_ext_temp(struct mgos_mel_ac *mel, float temp);
+bool mgos_mel_ac_set_fan(struct mgos_mel_ac *mel, enum mgos_mel_ac_param_fan fan);
+bool mgos_mel_ac_set_vane_vert(struct mgos_mel_ac *mel,
                             enum mgos_mel_ac_param_vane_vert vane_vert);
-void mgos_mel_ac_set_vane_horiz(struct mgos_mel_ac *mel,
+bool mgos_mel_ac_set_vane_horiz(struct mgos_mel_ac *mel,
                              enum mgos_mel_ac_param_vane_horiz vane_horiz);
 void mgos_mel_ac_set_params(struct mgos_mel_ac *mel, struct mgos_mel_ac_params *params);
 ```
 
+Setter function returns `false` in case of invalid argument values
+
 It's currently tested on `ESP8266` platform. More is coming
 
 For a complete demonstration of the driver, look at this [Mongoose App](https://github.com/mongoose-os-apps/mel-ac-demo)