Update Powershell Instructions for VPN connection (#350). Fixes #329

* Update Powershell Instructions for VPN connection

Update the Powershell instructions for creating the Windows VPN
connection.  Clarfied requirement that Powershell run as Administrator,
and additional steps required to update the Execution Policies for
PowerShell.

* Formatting updates

Cleaned up capitalization and spacing errors, as well as improved
wording a bit.

* Missed an S

Evil, evil capitalization.

README.md

@@ -101,7 +101,15 @@ You need to install the [strongSwan VPN Client for Android 4 and newer](https://
 
 ### Windows
 
-Copy the CA certificate, user certificate, and the user PowerShell script to the client computer. Import the CA certificate to the local machine Trusted Root certificate store. Then, run the included PowerShell script to import the user certificate, set up a VPN connection, and activate stronger ciphers on it.
+Copy the CA certificate, user certificate, and the user PowerShell script to the client computer. Import the CA certificate to the local machine Trusted Root certificate store. Then, run the included PowerShell script to import the user certificate, set up a VPN connection, and activate stronger ciphers on it. 
+The PowerShell script has to be run as Administrator, so first open PowerShell as Administrator, then navigate to your copied files. If you have never used PowerShell before, you will need to change the Execution Policy to allow unsigned scripts to run. Execute the following command in PowerShell to do so.
+```powershell
+Set-ExecutionPolicy Unrestricted -Scope CurrentUser
+```
+After you execute the user script remember to revert the policy change before you close the PowerShell window.
+```powershell
+Set-ExecutionPolicy Restricted -Scope CurrentUser
+```
 
 If you want to perform these steps by hand, you will need to import the user certificate to the Personal certificate store, add an IKEv2 connection in the network settings, then activate stronger ciphers on it via the following PowerShell script: