add language dropdown example

Author: dks333

components/code-groups.mdx

@@ -30,7 +30,7 @@ class HelloWorld {
 
 ## Language dropdown
 
-You can replace the tabs in a code group with a dropdown menu to toggle between languages.
+You can replace the tabs in a code group with a dropdown menu to toggle between languages using `dropdown` prop.
 
 <CodeGroup dropdown>
 
@@ -52,11 +52,28 @@ class HelloWorld {
 
 </CodeGroup>
 
-### Props
 
-<ResponseField name="dropdown" type="boolean">
-  Whether to show a dropdown button to toggle the code groups with languages as the options.
-</ResponseField>
+````mdx
+<CodeGroup dropdown>
+
+```javascript helloWorld.js
+console.log("Hello World");
+```
+
+```python hello_world.py
+print('Hello World!')
+```
+
+```java HelloWorld.java
+class HelloWorld {
+    public static void main(String[] args) {
+        System.out.println("Hello, World!");
+    }
+}
+```
+</CodeGroup>
+````
+
 
 <RequestExample>