Updating gemspec to reference README.md instead of README

Author: mcloonan

adwords_api/google-adwords-api.gemspec

@@ -36,7 +36,7 @@ Gem::Specification.new do |s|
   s.rubyforge_project = 'google-adwords-api'
   s.require_path = 'lib'
   s.files = Dir.glob('{lib,test}/**/*') + Dir.glob('examples/v*/**/*') +
-      %w(COPYING README ChangeLog adwords_api.yml)
+      %w(COPYING README.md ChangeLog adwords_api.yml)
   s.test_files = ['test/suite_unittests.rb']
   s.add_dependency('google-ads-common', '~> 0.9.3')
 end