Add docs for entities

sea_transport/entities/ISerializable.h

@@ -3,10 +3,23 @@
 
 #include <QDataStream>
 
-
+/**
+ * @brief Interface for any serializable object
+ * 
+ */
 class ISerializable {
 public:
+    /**
+     * @brief Write-obect-to-disk function
+     * 
+     * @param output output stream
+     */
     virtual void serialize(QDataStream &output) = 0;
+    /**
+     * @brief Read-object-from-disk function
+     * 
+     * @param input input stream
+     */
     virtual void deserialize(QDataStream &input) = 0;
 };