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

Author: stegag

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

@@ -14,6 +14,14 @@ The following configuration was used for the steps below:
 
 Use the following commands to install the required strongSwan configuration:
 
+```
+sudo apt-get update
+```
+
+```
+sudo apt-get upgrade
+```
+
 ```
 sudo apt install strongswan
 ```
@@ -32,4 +40,4 @@ Use the following command to install the Azure command-line interface:
 curl -sL https://aka.ms/InstallAzureCLIDeb | sudo bash
 ```
 
-For more information, see [Additional instructions to install the Azure CLI](/cli/azure/install-azure-cli-apt). 
+For more information, see [Additional instructions to install the Azure CLI](/cli/azure/install-azure-cli-apt).