code spell checking - part3 (usermods)

if you can spell Fahrenheit, you can't spell Celsius. And vice versa :-)

usermods/sht/usermod_sht.h

@@ -331,7 +331,7 @@ void ShtUsermod::loop()
 /**
  * Whenever MQTT is connected, publish HA autodiscovery topics.
  *
- * Is only donce once.
+ * Is only done once.
  *
  * @see Usermod::onMqttConnect()
  * @see UsermodManager::onMqttConnect()