Make it possible to add multiple CORS origins in discourse.conf and docker yml files

config/initializers/08-rack-cors.rb

@@ -3,7 +3,7 @@ if GlobalSetting.enable_cors
 
   Rails.configuration.middleware.use Rack::Cors do
     allow do
-      origins GlobalSetting.cors_origin
+      origins GlobalSetting.cors_origin.split(',').map(&:strip)
       resource '*', headers: :any, methods: [:get, :post, :options]
     end
   end