Add section describing how to install Ruby and gems using a package manager

TESTING.md

@@ -6,6 +6,18 @@ The mustache.js test suite uses the [RSpec](http://rspec.info/) testing
 framework. In order to run the tests you'll need to install [Ruby](http://ruby-lang.org/)
 as well as the `rake`, `rspec` (>=2), and `json` [RubyGems](http://rubygems.org/).
 
+### How to install Ruby, Ruby gems and the required gems with a package manager
+
+Tested on Ubuntu 10.10.
+
+    $ sudo apt-get install ruby1.8-dev
+    $ sudo apt-get install rubygems1.8
+    $ sudo gem install rake rspec
+
+    $ # needed to build native json extension for json gem
+    $ sudo apt-get install build-essential libreadline5-dev
+    $ sudo gem install json
+
 ### How to install Ruby and the required gems from source
 
 Make sure you have the required tools to compile it: