fix grammar typo

Author: flynnduism

themes/clean-landing/layouts/partials/oldnew.html

@@ -15,7 +15,7 @@ <h3>Cloud-native development</h3>
               <h2 class="is-2">Microservices Are Complicated.</h2>
               <ol>
                 <li>Developers have to spend more and more time on their app’s infrastructure tooling - images, registries, versioning, etc.</li>
-                <li>Security, performance and configuration concerns are becoming more blurred with the app development processes.</li>
+                <li>Security, performance, and configuration concerns are becoming more blurred with the app development processes.</li>
                 <li>Decisions about where you run your  microservices can impact on how you configure and develop your app.</li>
               </ol>
             </div>