[Doc] Correct how to run tests (#21)

Author: kachick

README.md

@@ -47,7 +47,7 @@ p s.scan(/\w+/) # -> nil
 
 ## Development
 
-After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
+After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake` to compile this and run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
 
 To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).