Fix custom field path in the manifest for advanced plugin

rules_shipping_advanced.xml

@@ -25,7 +25,7 @@
 
     <!-- VM 3.0 support (fields rather than params): -->
     <vmconfig>
-        <fields name="params" addfieldpath="/plugins/vmshipment/rules_shipping/fields">
+        <fields name="params" addfieldpath="/plugins/vmshipment/rules_shipping_advanced/fields">
             <fieldset name="shipment" label="OTSHIPMENT_RULES_PLUGIN_ADV" addfieldpath="/administrator/components/com_virtuemart/fields">
                 <field type="vmcurl"/>
                 <field type="spacer" default="OTSHIPMENT_RULES_PLUGIN_ADV" level="level1"/>