Add docs for UI Components inside widgets

Author: graschik

README.md

@@ -31,7 +31,8 @@ php bin/magento setup:static-content:deploy
 ## Usage Documentation
 - UI Components
   - [Entities Selector](docs/ui-components/entities-selector/README.md)
-- Widgets (coming soon)
+- Widgets
+  - `[Using UI Components Inside Widgets](docs/widgets/using-ui-components/README.md)`
 
 ## The MIT License
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)

docs/widgets/using-ui-components/README.md

@@ -0,0 +1,29 @@
+<h1>Using UI Components Inside Widgets</h1>
+
+## What are the benefits?
+- You can use UI components inside widgets instead of limited functionality of widgets.
+- You don't need to worry about data storage as the data is automatically stored inside the widgets.
+- Easy to configure.
+
+![](demo.gif)
+
+## Example
+You can see an example of a widget with most of the available UI components. The widget is called "[Example Widget with UI Components](../../../etc/widget.xml)". 
+
+## How to use it?
+- Create [app/code/Vendor/Module/etc/widget.xml](../../../etc/widget.xml) file inside your module.
+    - You have to add only one parameter ```block``` with class ```Grasch\AdminUi\Block\Adminhtml\Widget\Ui\Components```.
+    - ```namespace``` is the name of your form.xml file.
+  ```xml
+     <parameters>
+            <parameter name="component_data" xsi:type="block">
+                <block class="Grasch\AdminUi\Block\Adminhtml\Widget\Ui\Components">
+                    <data>
+                        <item name="namespace" xsi:type="string">widget_example_form</item>
+                    </data>
+                </block>
+            </parameter>
+        </parameters>
+  ```
+- Create [app/code/Vendor/Module/view/adminhtml/ui_component/form.xml](../../../view/adminhtml/ui_component/widget_example_form.xml) file inside your module. Add the UI Components that you need here.
+    - Use this class ```Grasch\AdminUi\DataProvider\Widget\DataProvider``` as ```dataProvider``` for your form.