Merge pull request #20708 from sikachu/update-pluck-suggestion

Update .pluck documentation on uniq

activerecord/lib/active_record/relation/calculations.rb

@@ -139,7 +139,7 @@ def calculate(operation, column_name)
     #   # SELECT people.id, people.name FROM people
     #   # => [[1, 'David'], [2, 'Jeremy'], [3, 'Jose']]
     #
-    #   Person.pluck('DISTINCT role')
+    #   Person.uniq.pluck(:role)
     #   # SELECT DISTINCT role FROM people
     #   # => ['admin', 'member', 'guest']
     #