Verbose instructions in ruby_basics

[kellydanma]

The instructions for running a test suite are verbose for sections with 1 file. It may be worth explaining to students that bundler is aware of all *_spec.rb files.

For example, the following suffices when there is a single *_spec.rb file :

$ cd 6_arrays
$ bundle exec rspec

This could be added as a tip after the current usage instructions. Note that the same command will execute all *_spec.rb files if there are multiple, so specifying the path is still a good way to run a single test file.

[KevinMulhern]

Thanks for the suggestion @kellydanma, thats a good point. I think we should include that in the instructions too :)

[wise-king-sullyman]

I can take this on if nobody else has yet.