Add (still incomplete) RDoc.

Rakefile

@@ -1,6 +1,8 @@
 require 'rake/extensiontask'
 require 'rake/testtask'
 
+require 'rdoc/task'
+
 require 'rubygems/package_task'
 
 spec = Gem::Specification.load('ruby-lxc.gemspec')
@@ -11,6 +13,12 @@ Rake::ExtensionTask.new('lxc', spec) do |ext|
   ext.lib_dir = 'lib/lxc'
 end
 
+Rake::RDocTask.new do |rd|
+  rd.main = 'ext/lxc/lxc.c'
+  rd.rdoc_dir = 'doc'
+  rd.rdoc_files.include(FileList['ext/lxc/lxc.c'])
+end
+
 Rake::TestTask.new do |t|
   t.libs << 'test'
   t.test_files = FileList['test/test_*.rb']