Clarify what this package is

README.md

@@ -23,6 +23,10 @@
   <a href="https://stackblitz.com/edit/vercel-next-js-bmc6dm?file=ui%2FTssLogo.tsx">Playground</a>
 </p>
 
+> You can think of `tss-react` as `@emotion/jss`.  
+> It's, in essence, [the JSS API](https://cssinjs.org/?v=v10.10.0#react-jss-example) but powered by Emotion.  
+> Just like `@emotion/styled` is the [styled-components API](https://styled-components.com/) but powered by Emotion.
+
 -   🚀 Seamless integration with [MUI](https://mui.com).
 -   🌐 Works in [Next.js App and Page Router](https://docs.tss-react.dev/ssr/next.js).
 -   🙅‍♂️ No custom styling syntax to learn, no shorthand, just plain CSS.