Add comment about object notation

Signed-off-by: Pekka Helenius <fincer89@hotmail.com>

bookstore/src/main/resources/templates/booklist.html

@@ -51,6 +51,11 @@ Idea of the following syntax used in this and other HTML document:
 		page.title.webform.list
 		</h1>
 
+		<!--/*
+		TODO: Use proper object notation here?
+		For example syntax, see
+		https://www.thymeleaf.org/doc/tutorials/2.1/usingthymeleaf.html#order-details
+		*/-->
 		<table class="table table-striped">
 
 			<tr>