add forward declaration examples

add class & inheritance examples

CPlusPlus/Classes/Entity.h

@@ -0,0 +1,14 @@
+#pragma once
+#include <string>
+
+class Entity
+{
+public:
+	Entity();
+	Entity(std::string name);
+
+	virtual std::string ToString();
+
+	std::string name = "";
+
+}; // IMPORTANT: semicolon at the end