Rename to match actual action

app/helpers/notifications_helper.rb

@@ -2,7 +2,7 @@ module NotificationsHelper
   def event_notification_title(event)
     if event.commented?
       "RE: " + event.card.title
-    elsif event.assignment?
+    elsif event.assigned?
       "Assigned to you: " + event.card.title
     else
       event.card.title

app/models/event.rb

@@ -12,7 +12,7 @@ class Event < ApplicationRecord
 
   after_create -> { card.touch(:last_active_at) }
 
-  def assignment?
+  def assigned?
     action == "assigned" || initial_assignment?
   end