delete the unnecessary word

docs/env_vars.md

@@ -19,7 +19,7 @@ Some features can only be accessed by environment variables, here is a list of t
 
 * **MINIKUBE_REMINDERWAITPERIODINHOURS** - (int) sets the number of hours to check for an update notification
 
-* **CHANGE_MINIKUBE_NONE_USER** - (bool) automatically change ownership of of ~/.minikube to the value of $SUDO_USER
+* **CHANGE_MINIKUBE_NONE_USER** - (bool) automatically change ownership of ~/.minikube to the value of $SUDO_USER
 
 * **MINIKUBE_ENABLE_PROFILING** - (int, `1` enables it) enables trace profiling to be generated for minikube