Enhancements in clarity to access-application-cluster/connecting-frontend-backend.md (#25927)

* Enhancements in clarity to docs/tasks/access-application-cluster/connecting-frontend-backend.md

* Code review comments

* Reverting name of service due to backed value in Dockerimage

content/en/examples/service/access/frontend-nginx.conf

@@ -0,0 +1,14 @@
+# The identifier Backend is internal to nginx, and used to name this specific upstream
+upstream Backend {
+    # hello is the internal DNS name used by the backend Service inside Kubernetes
+    server hello;
+}
+
+server {
+    listen 80;
+
+    location / {
+        # The following statement will proxy traffic to the upstream named Backend
+        proxy_pass http://Backend;
+    }
+}