doc(README): add mention on how to install and enable Pytorch/Jetstream

README.md

@@ -47,6 +47,17 @@ incoming HTTP requests and execute them on Cloud TPUs.
 
 Please see the [TGI specific documentation](text-generation-inference) on how to get started.
 
+### JetStream Pytorch Engine
+
+`optimum-tpu` provides an optional support of JetStream Pytorch engine inside of TGI. This support can be installed using the dedicated command:
+
+```shell
+pip install "optimum-tpu[jetstream-pt]" -f https://storage.googleapis.com/jax-releases/jax_nightly_releases.html \
+    -f https://storage.googleapis.com/jax-releases/jaxlib_nightly_releases.html
+```
+
+To enable the support, export the environment variable `JETSTREAM_PT=1`.
+
 ## Training
 
 Fine-tuning is supported and tested on the TPU `v5e`. We have tested so far: