Update documentation

Contains notes about future changes to `enable_if` guards, explaining
where this is going.

src/Stream/Writer.h

@@ -42,10 +42,15 @@ namespace Stream
 			WriteImplementation(vector.data(), vector.size() * sizeof(T));
 		}
 
-		// Vector of non trivially copyable data types
+		// Arbitrary container of writeable data types
 		template<typename T>
 		inline
-		std::enable_if_t<!std::is_trivially_copyable<typename T::value_type>::value>
+		std::enable_if_t<
+			// The enable_if check needs to change to something like:
+			// is_iterable<T> && is_writeable<typename T::value_type>
+			// For now, we leave the old check to avoid ambiguity
+			!std::is_trivially_copyable<typename T::value_type>::value
+		>
 		Write(const T& container) {
 			// Loop over all elements and call custom serializer for type
 			for (const auto& element : container) {