TESTING.md in airbrake-3.1.0 vs TESTING.md in airbrake-3.1.1

@@ -15,9 +15,14 @@
 Then, to start the suite, run
 
     rake
     # NOT: bundle exec rake
 
+Finally, this test suite runs against many rails versions. If you
+prefer to run it against specific version hit
+
+    rake cucumber:rails:<VERSION>
+
 
 For Maintainers
 ================
 
 When developing the Airbrake gem, be sure to use the integration test against an existing project on staging before pushing to master.