Fix links in SUMMARY

Author: rnestler

SUMMARY.md

@@ -19,7 +19,8 @@
       - [Push to Git Repository](ruby_on_rails/first_git_push.md)
       - [Initialise Gitflow](ruby_on_rails/initialise_gitflow.md)
       - [Configure Git Repository](configure_git_repository.md)
-      - [Create an Application Server](ruby_on_rails/create_application_server.md)
+      - [Create an Application Server (Heroku)](ruby_on_rails/create_application_server_heroku.md)
+      - [Create an Application Server (Deploio)](ruby_on_rails/create_application_server_deploio.md)
       - [Configure the CI/CD](ruby_on_rails/configure_ci.md)
   - [Tools]()
       - [RSpec](ruby_on_rails/rspec.md)