Update README.md

Author: xushiwei

gsh/README.md

@@ -23,7 +23,7 @@ You don't need a `go.mod` file, just enter `gop run ./example.gsh` directly to r
 
 It's strange to you that the file extension of Go+ source is not `.gop` but `.gsh`. It is only because Go+ register `.gsh` as a builtin [classfile](https://github.com/goplus/gop/blob/main/doc/classfile.md).
 
-We can change `./example.gsh` more complicated:
+We can change [example.gsh](demo/example/example.gsh) more complicated:
 
 ```coffee
 type file struct {