[FIX] stock_manual_transfer: Missing label in routes view

The fields for `warehouses_selectable` and `manual_transfers_selectable`
were placed on a single line. There was no clarity on what they represented,
as they were just two checkboxes without the appropriate labels.

Therefore, `manual_transfers_selectable` was placed on its own line.

stock_manual_transfer/views/stock_route_views.xml

@@ -5,7 +5,7 @@
         <field name="model">stock.route</field>
         <field name="inherit_id" ref="stock.stock_location_route_form_view" />
         <field name="arch" type="xml">
-            <xpath expr="//field[@name='warehouse_selectable']" position="after">
+            <xpath expr="//div[field[@name='warehouse_selectable']]" position="after">
                 <field name="manual_transfer_selectable" string="Manual transfers" />
             </xpath>
         </field>