Cleanup link in README.md

Author: nhooyr

README.md

@@ -32,7 +32,7 @@ go get nhooyr.io/websocket@v1.5.0
 
 For a production quality example that shows off the full API, see the [echo example on the godoc](https://godoc.org/nhooyr.io/websocket#example-package--Echo). On github, the example is at [example_echo_test.go](./example_echo_test.go).
 
-Please use the [golang.org/x/xerrors](https://godoc.org/golang.org/x/xerrors#As) package to check for [websocket.CloseError](https://godoc.org/nhooyr.io/websocket#CloseError). See the [CloseError godoc example](https://godoc.org/nhooyr.io/websocket#example-CloseError).
+Please use the [golang.org/x/xerrors.As](https://godoc.org/golang.org/x/xerrors#As) package to check for [websocket.CloseError](https://godoc.org/nhooyr.io/websocket#CloseError). See the [CloseError godoc example](https://godoc.org/nhooyr.io/websocket#example-CloseError).
 
 ### Server