fix funnel form theme path

Author: solverat

docs/OutputWorkflow/Funnel/10_FunnelLayer.md

@@ -134,8 +134,8 @@ Formbuilder.extjs.formPanel.outputWorkflow.funnelLayer.dummyLayer = Class.create
 
 #### Twig Partial
 ```twig
-{% if formTheme is not null %}
-    {% form_theme form with (formTheme ~ '.html.twig') only %}
+{% if formThemePath is not null %}
+    {% form_theme form formThemePath %}
 {% endif %}
 
 {% block funnel_content %}

src/FormBuilderBundle/Resources/views/funnel/layer/simple_layout_layer.html.twig

@@ -1,5 +1,5 @@
-{% if formTheme is not null %}
-    {% form_theme form with [formTheme ~ '.html.twig'] only %}
+{% if formThemePath is not null %}
+    {% form_theme form formThemePath %}
 {% endif %}
 
 {% block funnel_content %}