docs: add demo

liuchuzhang · liuchuzhang · commit 39e04196eb76 · 2021-02-27T12:51:22.000+08:00
diff --git a/README.md b/README.md
@@ -59,3 +59,4 @@ webpack config
 }
 ```
 
+[demo](https://github.com/liuchuzhang/react-css-modules-file/tree/main/demo/css-modules)

Original file line number	Diff line number	Diff line change
`@@ -59,3 +59,4 @@ webpack config`
`59`	`59`	`}`
`60`	`60`	```
`61`	`61`
	`62`	`+[demo](https://github.com/liuchuzhang/react-css-modules-file/tree/main/demo/css-modules)`