Merge pull request rails#52095 from ioquatix/rack-version-constant

Print `Rack.release` as part of default Rails welcome page.

Author: rafaelfranca

railties/lib/rails/templates/rails/welcome/index.html.erb

@@ -85,6 +85,7 @@
 
   <ul>
     <li><strong>Rails version:</strong> <%= Rails.version %></li>
+    <li><strong>Rack version:</strong> <%= Rack.release %></li>
     <li><strong>Ruby version:</strong> <%= RUBY_DESCRIPTION %></li>
   </ul>
 </body>