Add standalone instantiation documentation

docs/getting-started.md

@@ -25,9 +25,17 @@ Here's how you create an instance of Smarty in your PHP scripts:
 ```php
 <?php
 
+// Instantiated via composer
 require 'vendor/autoload.php';
 use Smarty\Smarty;
 $smarty = new Smarty();
+
+// or ...
+
+// Instantiated directly
+require("/path/to/smarty/src/Smarty.class.php");
+use Smarty\Smarty;
+$smarty = new Smarty();
 ```
 
 Now that the library files are in place, it's time to set up the Smarty