Add Qwen3 notebook to docs

Author: jonatanklosko

mix.exs

@@ -63,6 +63,7 @@ defmodule Bumblebee.MixProject do
         "notebooks/stable_diffusion.livemd",
         "notebooks/llms.livemd",
         "notebooks/llms_rag.livemd",
+        "notebooks/qwen3.livemd",
         "notebooks/fine_tuning.livemd",
         "examples/phoenix/README.md"
       ],

notebooks/qwen3.livemd

@@ -8,7 +8,7 @@ Mix.install([
   {:kino, "~> 0.14.0"}
 ])
 
-Nx.global_default_backend({EXLA.Backend, client: :host})
+Nx.global_default_backend(EXLA.Backend)
 ```
 
 ## Introduction