Some fixes in rails guides generation

* Passing edge information to the views fixes the lack of the edge badge
and sets the appropriate welcome page on edgeguides.rubyonrails.org.
* Changes in the welcome message to hyper link the rails tree based on
the version.
* Mention the Amazon url from where kindlegen can be downloaded.

railties/guides/rails_guides/generator.rb

@@ -49,8 +49,8 @@
 #
 #   KINDLE
 #     Set to "1" to generate the .mobi with all the guides. The kindlegen
-#     executable must be in your PATH. Google for it if you do not have it
-#     locally, it is available from Amazon for free.
+#     executable must be in your PATH. You can get it for free from
+#     http://www.amazon.com/kindlepublishing
 #
 # ---------------------------------------------------------------------------
 
@@ -199,7 +199,7 @@ def generate_guide(guide, output_file)
       layout = kindle? ? 'kindle/layout' : 'layout'
 
       File.open(output_path, 'w') do |f|
-        view = ActionView::Base.new(source_dir, :version => @version, :mobi => "kindle/#{mobi}")
+        view = ActionView::Base.new(source_dir, :edge => @edge, :version => @version, :mobi => "kindle/#{mobi}")
         view.extend(Helpers)
 
         if guide =~ /\.(\w+)\.erb$/

railties/guides/source/_welcome.html.erb

-<h2>Ruby on Rails Guides (<%= @version %>)</h2>
+<h2>Ruby on Rails Guides</h2>
 
 <% if @edge %>
 <p>
-  These are <b>Edge Guides</b>, based on the current
-  <a href="https://github.com/rails/rails/tree/master">master branch</a>.
+  These are <b>Edge Guides</b>, based on the current <a href="https://github.com/rails/rails/tree/<%= @version %>">master</a> branch.
 </p>
 <p>
-  If you are looking for the ones for the stable version please check
+  If you are looking for the ones for the stable version, please check
   <a href="http://guides.rubyonrails.org">http://guides.rubyonrails.org</a> instead.
 </p>
 <% else %>
 <p>
-  These are the new guides for Rails 3. The guides for Rails 2.3 are still available
-  at <a href="http://guides.rubyonrails.org/v2.3.11/">http://guides.rubyonrails.org/v2.3.11/</a>.
+  These are the new guides for Rails 3.1 based on <a href="https://github.com/rails/rails/tree/<%= @version %>"><%= @version %></a>.
+  These guides are designed to make you immediately productive with Rails, and to help you understand how all of the pieces fit together.
 </p>
 <% end %>
 <p>
-  These guides are designed to make you immediately productive with Rails,
-  and to help you understand how all of the pieces fit together.
+  The guides for Rails 2.3.x are available at <a href="http://guides.rubyonrails.org/v2.3.11/">http://guides.rubyonrails.org/v2.3.11/</a>.
 </p>