Use of PhantomJS on Ruby Rspec guide

[megatux]

Affected Guide:

• ruby/rspec/tutorial.md#feature-specs

Describe your motive to discuss:

It states the use of PhantomJS but I think this tool has been discontinued on 2018.

Describe the solution you propose

Maybe recommend the use of Chrome/ium in headless mode?

Describe alternatives you've considered

Chrome or FF headless

Additional context

More info:

• https://phantomjs.org/
• https://en.wikipedia.org/wiki/PhantomJS