update gotutorial a bit

go/gotutorial.md

@@ -91,7 +91,7 @@ message Point {
 
 Next we need to generate the gRPC client and server interfaces from our .proto service definition. We do this using the protocol buffer compiler `protoc` with a special gRPC Go plugin.
 
-For simplicity, we've provided a [bash script](https://github.com/grpc/grpc-go/blob/master/codegen.sh) that runs `protoc` for you with the appropriate plugin, input, and output (if you want to run this yourself, make sure you've installed protoc and followed the gRPC code [installation instructions](https://github.com/grpc/grpc/blob/master/INSTALL) first):
+For simplicity, we've provided a [bash script](https://github.com/grpc/grpc-go/blob/master/codegen.sh) that runs `protoc` for you with the appropriate plugin, input, and output (if you want to run this by yourself, make sure you've installed protoc and followed the [installation instructions](https://github.com/grpc/grpc-go/blob/master/README.md) first):
 
 ```shell
 $ codegen.sh route_guide.proto