Update references in readme to point to new location

Author: awensaunders

db/data_migration/v2.11.1/README.md

@@ -1,4 +1,4 @@
-# Migrations in 2.12
+# Migrations in 2.11.1
 
 This migration updates the configuration of GBV instances *only*. This migrates the fields that calculate average scores on subforms to new versions which support decimal places.
 
@@ -9,5 +9,5 @@ These scripts will update the `Field` records where calculations exist.
 To validate which fields will be updated, run the following:
 
 ```bash
-rails r ./db/migrations/v2.12/update_calculated_avg_fields_gbv.rb
+rails r ./db/migrations/v2.11.1/update_calculated_avg_fields_gbv.rb
 ```