Update gRPC C++ doc link in grpc_server example

PiperOrigin-RevId: 271397984
Change-Id: Ia50a41aeb25798507395cbc22ab2828ebfff51c9

asylo/examples/grpc_server/README.md

@@ -25,7 +25,7 @@ with it from a client running in an untrusted environment.
 This guide assumes that you are familiar with:
 
 *   The [Asylo quickstart guide](https://asylo.dev/docs/guides/quickstart.html)
-*   The [gRPC C++ basics](https://grpc.io/docs/tutorials/basic/c.html) tutorial
+*   The [gRPC C++ basics](https://grpc.io/docs/tutorials/basic/cpp) tutorial
 *   [Protocol Buffers](https://developers.google.com/protocol-buffers/)
 *   The C++ language