Put links to factories readme back

spec/factories/call_for_papers.rb

@@ -1,3 +1,5 @@
+# Read about factories at https://github.com/thoughtbot/factory_girl
+
 FactoryGirl.define do
   factory :call_for_papers do
     start_date Date.today - 1

spec/factories/conferences.rb

@@ -1,3 +1,5 @@
+# Read about factories at https://github.com/thoughtbot/factory_girl
+
 FactoryGirl.define do
   factory :conference do
     title 'The dog and pony show'

spec/factories/users.rb

@@ -1,3 +1,5 @@
+# Read about factories at https://github.com/thoughtbot/factory_girl
+
 FactoryGirl.define do
   factory :user do
     email 'example@example.com'