Update ports-and-protocols.md

Author: sarangjo

content/en/docs/reference/ports-and-protocols.md

@@ -7,7 +7,7 @@ weight: 50
 When running Kubernetes in an environment with strict network boundaries, such 
 as on-premises datacenter with physical network firewalls or Virtual 
 Networks in Public Cloud, it is useful to be aware of the ports and protocols 
-used by Kubernetes components
+used by Kubernetes components.
 
 ## Control plane