Fix typo: 'this also mean' -> 'this also means'

activerecord/lib/active_record/relation/batches.rb

@@ -40,7 +40,7 @@ def find_each(options = {})
     #
     # It's not possible to set the order. That is automatically set to
     # ascending on the primary key ("id ASC") to make the batch ordering
-    # work. This also mean that this method only works with integer-based
+    # work. This also means that this method only works with integer-based
     # primary keys. You can't set the limit either, that's used to control
     # the batch sizes.
     #