README: how run specific test

Author: erikw

README.md

@@ -115,6 +115,7 @@ After checking out the repo;
 1. Install [RVM](https://rvm.io/rvm/install) and install a supported ruby version (see .gemspec)
 1. run `scripts/setup` to install dependencies
 1. run `scripts/test` to run the tests
+   * Run a specific test with `bundle exec rspec -e "name of test example"`
 1.  You can also run `scripts/console` for an interactive prompt that will allow you to experiment.
 
 To install this gem onto your local machine, run `bundle exec rake install`.