fix typo in k (ahmetb#88)

09-allow-traffic-only-to-a-port.md

@@ -17,7 +17,7 @@ A port may be either a numerical or named port on a pod.
 
 Run a web server pod called `apiserver`:
 
-    kubectl run piserver --image=ahmet/app-on-two-ports --labels="app=apiserver"
+    kubectl run apiserver --image=ahmet/app-on-two-ports --labels="app=apiserver"
 
 This application returns a hello response to requests on `http://:8000/`
 and a monitoring metrics response on `http://:5000/metrics`.