document everything except InternalDisplay and IoT

ESPMegaPRO-firmware/lib/ESPMegaPRO/ExpansionCard.hpp

@@ -1,6 +1,17 @@
 #pragma once
 #include <Arduino.h>
 
+/**
+ * @brief The base class for all expansion cards
+ * 
+ * In order to create a new expansion card, you should create a new class that inherits from this class.
+ * Your class should implement the following functions:
+ * - begin() : Initialize the card
+ * - loop() : A function that is called in the main loop
+ * - getType() : Get the type of the card, The type should be a unique number between 0 and 255
+ * 
+ * @warning This class is abstract and should not be instantiated directly.
+ */
 class ExpansionCard {
     public:
         // Instantiate the card with the specified address