anchor.diff:  
   == Prerequisites
   
  -All that's needed is Ruby 1.9.3 or better and a few RubyGems, which we explain how to install in the next section.
  +All that's needed is Ruby 1.9.3 or better (2.1.2 recommended) and a few RubyGems, which we explain how to install in the next section.
   
   To check you have Ruby available, use the +ruby+ command to query the version installed:
   
  
positive.code: 
  If it's not installed, use the +gem+ command to install it.
  
   $ gem install bundle
  
  Then use the +bundle+ command to install the project dependencies:
  
   $ bundle install
  
  You're now ready to use {project-name}.
  Let's grab an AsciiDoc document to distill.
  
  === Example AsciiDoc document
  
negative.code: 
  If you want to clone the git repository, simply copy the {project-repo-uri}[GitHub repository URL] and pass it to +git clone+ command:
  
   $ git clone https://github.com/asciidoctor/asciidoctor-pdf
  
  Next, change to the project directory:
  
  