Docs correction: MemoryCardSlot.read_card() is implemented

[saxbophone]

Marked as not implemented in the docs:

wondercard/wondercard/include/wondercard/MemoryCardSlot.hpp

Lines 67 to 73 in 795e7a7

	/**
	* @brief Reads the entire contents of the inserted card
	* @returns true/false indicating read sucess/failure
	* @param[out] data destination to write read data to
	* @warning Not Implemented
	*/
	bool read_card(std::span<Byte, MemoryCard::CARD_SIZE> data);