Update system.xml

Author: srenon

app/code/local/MagePal/GoogleTagManager/etc/system.xml

@@ -22,6 +22,7 @@
             <show_in_default>1</show_in_default>
             <show_in_website>1</show_in_website>
             <show_in_store>1</show_in_store>
+            <comment><![CDATA[Maximize Your Magento Potential with GA4: Upgrade Now and Unlock Cutting-Edge <a href="https://www.magepal.com/magento1/google-tag-manager-1.html">Google Analytics 4</a> Features.]]></comment>
             <groups>
                 <general translate="label">
                     <label>Google Tag Manager</label>