Added code to obtain service principal secret

Author: dcaro

docs-conceptual/azps-2.3.2/create-azure-service-principal-azureps.md

@@ -42,7 +42,14 @@ Without any other authentication parameters, password-based authentication is us
 $sp = New-AzADServicePrincipal -DisplayName ServicePrincipalName
 ```
 
-The returned object contains the `Secret` member, which is a `SecureString` containing the generated password. Make sure that you store this value somewhere secure to authenticate with the service principal. Its value __won't__ be displayed in the console output. If you lose the password, [reset the service principal credentials](#reset-credentials). 
+The returned object contains the `Secret` member, which is a `SecureString` containing the generated password. Make sure that you store this value somewhere secure to authenticate with the service principal. Its value __won't__ be displayed in the console output. If you lose the password, [reset the service principal credentials](#reset-credentials).
+
+The following code will allow you to export the secret:
+
+```azurepowershell-interactive
+$BSTR = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($sp.Secret)
+$UnsecureSecret = [System.Runtime.InteropServices.Marshal]::PtrToStringAuto($BSTR)
+```
 
 For user-supplied passwords, the `-PasswordCredential` argument takes `Microsoft.Azure.Commands.ActiveDirectory.PSADPasswordCredential` objects. These objects must have a valid `StartDate` and `EndDate`, and take a plaintext `Password`. When creating a password, make sure you follow the [Azure Active Directory password rules and restrictions](/azure/active-directory/active-directory-passwords-policy). Don't use a weak password or reuse a password.