'Asset Bundles' topic added to the docs.

docs/guide/README.md

@@ -21,6 +21,7 @@ Usage
 
 * [Yii widgets](usage-widgets.md)
 * [Html helper](helper-html.md)
+* [Asset Bundles](asset-bundles.md)
 
 Additional topics
 -----------------

docs/guide/asset-bundles.md

@@ -0,0 +1,16 @@
+Asset Bundles
+=============
+
+Bootstrap is a complex front-end solution, which includes CSS, JavaScript, fonts and so on.
+In order to allow you most flexible control over Bootstrap components, this extension provides several asset bundles.
+They are:
+
+- [[yii\bootstrap\BootstrapAsset|BootstrapAsset]] - contains only main CSS files.
+- [[yii\bootstrap\BootstrapPluginAsset|BootstrapPluginAsset]] - depends on [[yii\bootstrap\BootstrapAsset]], contains javascript files.
+- [[yii\bootstrap\BootstrapThemeAsset|BootstrapThemeAsset]] - depends on [[yii\bootstrap\BootstrapAsset]], contains Bootstrap default theme CSS.
+
+Particular application needs may require different bundle (or bundle combination) usage.
+If you need only CSS styles, [[yii\bootstrap\BootstrapAsset]] will be enough for you. However, if
+you want to use Bootstrap JavaScript, you need to register [[yii\bootstrap\BootstrapPluginAsset]].
+
+> Tip: most of the widgets register [[yii\bootstrap\BootstrapPluginAsset]] automatically.