docs: add webpack devServer config and useAnonymousSlot docs

src/docs/additional/additional.mdx

@@ -45,6 +45,30 @@ DireflowComponent.create({
 });
 ```
 
+## Anonymous Slot
+The Web Component Standard supports slot.
+In order to enable the anonymous slot, set the useAnonymousSlot property to `true` in the configuration. 
+So you can distribute your content(text or embed component) to a <slot></slot> tag.
+
+
+```javascript
+// src/cool-component/index.js
+DireflowComponent.create({
+  component: App,
+  configuration: {
+    tagname: 'cool-component',
+    useShadow: true,
+    useAnonymousSlot: true,
+  },
+});
+```
+```html
+<cool-component>
+  <div>I will be distributed to cool-component's inner slot tag.</div>
+</cool-component>
+```
+
+
 ## IE 11 Support
 
 In order to support IE 11, you will need to import the necessary polyfills.

src/docs/get-started/get-started.mdx

@@ -138,10 +138,20 @@ A Direflow Setup is using the same configuration as in [create-react-app](https:
 However, this file offers the ability to further override any of the Webpack config that ships with Direflow.  
 Simply add an override after the first line:
 ```javascript
-module.exports = (config, env) => ({
-  ...webpackConfig(config, env),
-  // Add your own webpack config here (optional)
-});
+module.exports = {
+  webpack: (config, env) => ({
+    ...webpackConfig(config, env),
+    // Add your own webpack config here (optional)
+  }),
+  devServer: (configFunction) => {
+    return function (proxy, allowedHost) {
+      // Add your own devServer proxy config here
+      // Such as proxy = {target: "/direflow", secure: false, changeOrigin: true }
+      const config = configFunction(proxy, allowedHost);
+      return config;
+    };
+  },
+};
 ```
 
 ## Access the DOM element