Add placeholder files for multisite functionality

includes/Multisite/README.md

@@ -0,0 +1,24 @@
+# Multisite Support
+
+This directory contains placeholder files for multisite-specific functionality. When developing a plugin based on this template, you can extend these files or create additional classes in this directory to implement multisite features.
+
+## Usage
+
+To implement multisite-specific functionality:
+
+1. Create your multisite-specific classes in this directory
+2. Load and initialize these classes in your main plugin file when in a multisite environment:
+
+```php
+// Load multisite support classes if in multisite environment
+if ( is_multisite() ) {
+    require_once WP_PLUGIN_STARTER_TEMPLATE_PATH . 'includes/Multisite/class-your-multisite-class.php';
+    
+    // Initialize multisite support
+    $your_multisite_class = new WPALLSTARS\PluginStarterTemplate\Multisite\Your_Multisite_Class();
+}
+```
+
+## Testing
+
+For information on testing your plugin in a multisite environment, see the [Testing Framework](.wiki/Testing-Framework.md) documentation.