Merge pull request #17201 from djpowers/patch-1

Fix grammar [ci skip]

guides/source/upgrading_ruby_on_rails.md

@@ -28,7 +28,7 @@ TIP: Ruby 1.8.7 p248 and p249 have marshaling bugs that crash Rails. Ruby Enterp
 
 Rails provides the `rails:update` rake task. After updating the Rails version
 in the Gemfile, run this rake task.
-This will help you with the creation of new files and changes of old files in a
+This will help you with the creation of new files and changes of old files in an
 interactive session.
 
 ```bash