OP-289: Add a helpbox explaining what "Is packed product" does

Author: hmfilar

src/Resources/translations/messages.en.yml

@@ -8,3 +8,4 @@ bitbag_sylius_product_bundle:
         products_in_bundle: Products in bundle
         is_packed_product: Is packed product
         is_bundle: Is bundle
+        is_packed_help: If the bundle is not marked as packed, customers will be able to select different variants for products in the bundle

src/Resources/views/Admin/Product/Tab/_bundle.html.twig

@@ -3,6 +3,10 @@
 <div class="ui tab" data-tab="bundle">
 
     {{ form_row(form.productBundle.isPackedProduct) }}
+    {{ form_help(form.productBundle.isPackedProduct, {
+        'help': 'bitbag_sylius_product_bundle.ui.is_packed_help'|trans,
+        'help_attr': {'class':'ui info message'}
+    }) }}
     {{ form_row(form.productBundle.productBundleItems) }}
 
     {{ sonata_block_render_event('sylius.admin.product.' ~ action ~ '.tab_bundle', {'form': form }) }}