create a new remark command

src/main/java/seedu/address/logic/commands/RemarkCommand.java

@@ -0,0 +1,16 @@
+package seedu.address.logic.commands;
+
+import seedu.address.model.Model;
+
+/**
+ * Changes the remark of an existing person in the address book.
+ */
+public class RemarkCommand extends Command {
+
+    public static final String COMMAND_WORD = "remark";
+
+    @Override
+    public CommandResult execute(Model model) {
+        return new CommandResult("Hello from remark");
+    }
+}