docs, use hash instead of a string for `order`. [ci skip]

Closes #21121

guides/source/active_record_basics.md

@@ -260,7 +260,7 @@ david = User.find_by(name: 'David')
 
 ```ruby
 # find all users named David who are Code Artists and sort by created_at in reverse chronological order
-users = User.where(name: 'David', occupation: 'Code Artist').order('created_at DESC')
+users = User.where(name: 'David', occupation: 'Code Artist').order(created_at: :desc)
 ```
 
 You can learn more about querying an Active Record model in the [Active Record