title: Mac OSX Ruby on Rails Installation problem - file not found / error with generating documentation
body: <p>I am installing Ruby on Rails on OSX.  I am following these instructions:</p>
  
  <pre><code>tp&gt; tar xzf rubygems-x.y.z.tar.gz
  tp&gt; cd rubygems-x.y.z
  rubygems-x.y.z&gt; sudo ruby setup.rb
  </code></pre>
  
  <p>All good up to here and then I issue with this command with the following error:</p>
  
  <pre><code>tp&gt; sudo gem install rails --include-dependencies
  INFO:  `gem install -y` is now default and will be removed
  INFO:  use --ignore-dependencies to install only the gems you list
  Successfully installed rails-3.0.5
  1 gem installed
  Installing ri documentation for rails-3.0.5...
  File not found: lib
  ERROR:  While generating documentation for rails-3.0.5
  ... MESSAGE:   exit
  ... RDOC args: --ri --op /Library/Ruby/Gems/1.8/doc/rails-3.0.5/ri lib --title rails-3.0.5 Documentation --quiet
  </code></pre>
  
  <p>Additional info:</p>
  
  <p>My version of Ruby:</p>
  
  <pre><code>sh-3.2# ruby -v
  ruby 1.8.7 (2009-06-12 patchlevel 174) [universal-darwin10.0]
  </code></pre>