Update UI link to new conflicts page

We now have a conflicts page that actually describes the problem
and the solutions for it - let's update the UI to link to it.

app/serializers/merge_request_widget_entity.rb

@@ -48,7 +48,7 @@ class MergeRequestWidgetEntity < Grape::Entity
   end
 
   expose :conflicts_docs_path do |merge_request|
-    help_page_path('user/project/merge_requests/resolve_conflicts.md')
+    help_page_path('user/project/merge_requests/conflicts.md')
   end
 
   expose :reviewing_and_managing_merge_requests_docs_path do |merge_request|