Support PDF syntax highlighting via enhanced Rouge

[petervwyatt]

Please enable [source,pdf] syntax highlighting via my enhanced version of Rouge (which, after 14 months, still has not been merged!!) by using this specific fork of Rouge

Gemfile addition:

# Pick up modified Rouge with "pdf" (COS) syntax support
gem "rouge", git: 'https://github.com/petervwyatt/rouge.git', branch: 'feature.pdf'

[ronaldtse]

I've followed up the request at the relevant issue:

• Add PDF syntax to Rouge rouge-ruby/rouge#2058

It's hard for us to "use an enhanced Rouge" because that means we need to fork Rouge and then publish it as a gem...