xSQLServerScript: Not obvious how to use Windows Authentication

[johlju]

Details of the scenario you try and problem that is occurring:
When using this resource with the Credential parameter it is not obvious how to use the resource if one wants to logon to the instance using Windows Authentication.

• Add to the description of the parameter Credential how to use Windows Authentication. And that it is controlled by parameter PsDscRunAsCredential. And without either Credential and PsDscRunAsCredential the account SYSTEM is used as the login.
• The following configurations should be added to the Examples folder

The DSC configuration that is using the resource (as detailed as possible):
The following configuration is logging in using SQL Authentication.

xSQLServerScript "$($currentSqlInstance)-RunSQLScript"
{
    ServerInstance = "localhost\Instance"
    SetFilePath = "C:\DSCTemp\SQLScripts\Set-RunSQLScript.sql"
    TestFilePath = "C:\DSCTemp\SQLScripts\Test-RunSQLScript.sql"
    GetFilePath = "C:\DSCTemp\SQLScripts\Get-RunSQLScript.sql"

    Credential = $SqlAdministratorCredential
}         

The following configuration is logging in using Windows Authentication with the account SYSTEM.

xSQLServerScript "$($currentSqlInstance)-RunSQLScript"
{
    ServerInstance = "localhost\Instance"
    SetFilePath = "C:\DSCTemp\SQLScripts\Set-RunSQLScript.sql"
    TestFilePath = "C:\DSCTemp\SQLScripts\Test-RunSQLScript.sql"
    GetFilePath = "C:\DSCTemp\SQLScripts\Get-RunSQLScript.sql"
}         

The following configuration is logging in using Windows Authentication with the provided credentials.

xSQLServerScript "$($currentSqlInstance)-RunSQLScript"
{
    ServerInstance = "localhost\Instance"
    SetFilePath = "C:\DSCTemp\SQLScripts\Set-RunSQLScript.sql"
    TestFilePath = "C:\DSCTemp\SQLScripts\Test-RunSQLScript.sql"
    GetFilePath = "C:\DSCTemp\SQLScripts\Get-RunSQLScript.sql"

    PsDscRunAsCredential = $SqlAdministratorCredential
}         

Version of the Operating System, SQL Server and PowerShell the DSC Target Node is running:
Windows Server 2012 R2, SQL Server 2008 R2 (with SQL Server 2016 SQLPS-module), PS 5.0

Version of the DSC module you're using, or 'dev' if you're using current dev branch:
Dev