Update vpn-gateway-strongswan-certificates-include.md

Author: stegag

includes/vpn-gateway-strongswan-certificates-include.md

@@ -27,7 +27,7 @@ Generate the user certificate.
 
   ```
   export PASSWORD="password"
-  export USERNAME="client"
+  export USERNAME=$(hostnamectl --static)
 
   ipsec pki --gen --outform pem > "${USERNAME}Key.pem"
   ipsec pki --pub --in "${USERNAME}Key.pem" | ipsec pki --issue --cacert caCert.pem --cakey caKey.pem --dn "CN=${USERNAME}" --san "${USERNAME}" --flag clientAuth --outform pem > "${USERNAME}Cert.pem"
@@ -37,4 +37,4 @@ Generate a p12 bundle containing the user certificate. This bundle will be used
 
   ```
   openssl pkcs12 -in "${USERNAME}Cert.pem" -inkey "${USERNAME}Key.pem" -certfile caCert.pem -export -out "${USERNAME}.p12" -password "pass:${PASSWORD}"
-  ```
+  ```