Add/Update install info

This is still WIP, but added/update new installation info about
asciidoctor.

README.md

@@ -161,23 +161,25 @@ make
    need to _full_ MacTex rather than just BasicTex.
 1. Add `/Library/TeX/texbin` to your `PATH`.
 1. `easy_install dblatex`
-1. Install [asciidoc](http://asciidoc.org/INSTALL.html)
+1. Install [asciidoc](https://github.com/asciidoctor/asciidoctor)
+1. Install [asciidoctor-pdf](https://github.com/asciidoctor/asciidoctor-pdf)
 1. Install [asciidoctor-diagram](http://asciidoctor.org/docs/asciidoctor-diagram/)
 1. Install [ditaa](https://github.com/stathissideris/ditaa)
 1. Install [source-highlight](https://www.gnu.org/software/src-highlite/)
 1. Install [wget](https://www.gnu.org/software/wget/)
 1. `make`
 
-### Mac OSX (using brew)
+### Mac OSX (using brew etc)
 
 1. `brew install Caskroom/cask/mactex`
 1. Add `/Library/TeX/texbin` to your `PATH`.
 1. `sudo easy_install dblatex`
-1. `brew install asciidoc`
+1. `brew install asciidoctor`
+1. `gem install asciidoctor-pdf`
+1. `gem install asciidoctor-diagram`
 1. `brew install ditaa`
 1. `brew install source-highlight`
 1. `brew install wget`
-1. `gem install asciidoctor-diagram`
 1. `make`
 
 ## License