docs: link to the hosted playgrounds from the README (#3)

* docs: link to the hosted playgrounds from the README

* docs: lead with the platform category, not the infrastructure

Author: chengzeyi

README.md

@@ -176,3 +176,8 @@ mvn test -Dtest=ClientTest#testInitWithApiKey
 ## License
 
 MIT
+
+---
+
+**[WaveSpeed AI](https://wavespeed.ai/)** — AI image & video generation platform.
+Try it in the browser: **[Image generator](https://wavespeed.ai/image-generator)** · **[Video generator](https://wavespeed.ai/video-generator)**