"Added javadoc to dialog enum"

src/main/java/no/ntnu/idatt1002/demo/controller/DialogMode.java

 package no.ntnu.idatt1002.demo.controller;
 
+/**
+ * Enum for distinguishing between adding or editing an item in a tableview
+ *
+ * @author Harry Linrui Xu
+ * @since 11.3.2023
+ */
 enum DialogMode {
-  ADD, EDIT, DELETE
+  ADD, EDIT
 }