Source attributes in output template (#45)

* Updated download options to take a media item; allowed for specifying custom output path template options

* Fixed bug where indexing job wouldn't run for the first time

* Renamed friendly_name to custom_name

* Added new options to default template and UI

* Improved explainer UI

lib/pinchflat_web/controllers/media_profiles/media_profile_html.ex

@@ -30,7 +30,13 @@ defmodule PinchflatWeb.MediaProfiles.MediaProfileHTML do
   end
 
   def custom_output_template_options do
-    ~w(upload_day upload_month upload_year)a
+    %{
+      upload_day: nil,
+      upload_month: nil,
+      upload_year: nil,
+      source_custom_name: "the name of the sources that use this profile",
+      source_collection_type: "the collection type of the sources that use this profile. Either 'channel' or 'playlist'"
+    }
   end
 
   def common_output_template_options do