README.md in lazy_migrate-0.2.0 vs README.md in lazy_migrate-0.3.0

@@ -72,11 +72,11 @@
 We use [Appraisal](https://github.com/thoughtbot/appraisal) to test the gem against different rails version like so:
 
 ```
 bundle exec appraisal
 
-bundle exec appraisal rails-5-1-5 rspec
-bundle exec appraisal rails-5-2-4-3 install
+bundle exec appraisal rails_5_1_5 rspec
+bundle exec appraisal rails_5_2_4_3 install
 ```
 
 ## Contributing
 
 Bug reports and pull requests are welcome on GitHub at https://github.com/jesseduffield/lazy_migrate.