straight forward placeholder

Co-authored-by: Marta Marczykowska-Górecka <marmarta@users.noreply.github.com>

Author: nihalxkumar

ui/newfwruledlg.ui

@@ -119,7 +119,7 @@
         <string>Comments are for user reference only</string>
        </property>
        <property name="placeholderText">
-        <string>Optional note (e.g. reason for this rule)</string>
+        <string>Comment (optional)</string>
        </property>
        <property name="maxLength">
         <number>512</number>