Document how to use Bazel Output Service

Now that Bazel 7.2 has been released, we can now document which exact
command line flags need to be provided to use this new feature.

README.md

@@ -251,7 +251,10 @@ directory. This means that you can enjoy the performance improvements of
 "Remote Builds without the Bytes", but not with the restrictions that it
 currently imposes.
 
-The Bazel Output Service protocol was added to the Bazel repository in
-[PR#21140](https://github.com/bazelbuild/bazel/pull/21140). It is
-expected that a client for the Bazel Output Service protocol is added to
-Bazel 7.2.
+Bazel 7.2 and later implement support for the Bazel Output Service.
+Bazel can be configured to use this feature by providing the following
+additional command line arguments:
+
+```
+--experimental_remote_output_service unix:${HOME}/.cache/bb_clientd/grpc --experimental_remote_output_service_output_path_prefix ${HOME}/bb_clientd/outputs
+```