Merge pull request #38774 from stevenjackson/patch-1

Update doc for #pluck to use non-deprecated syntax

[ci skip]

activerecord/lib/active_record/relation/calculations.rb

@@ -174,7 +174,7 @@ def calculate(operation, column_name)
     #   # SELECT people.id FROM people WHERE people.age = 21 LIMIT 5
     #   # => [2, 3]
     #
-    #   Person.pluck('DATEDIFF(updated_at, created_at)')
+    #   Person.pluck(Arel.sql('DATEDIFF(updated_at, created_at)'))
     #   # SELECT DATEDIFF(updated_at, created_at) FROM people
     #   # => ['0', '27761', '173']
     #