Reorder ML frameworks and support matrix items on website. (#15719)

* Alphabetize ML frameworks
* The JAX docs are sparse, so I could also see putting PyTorch at the
top of the list
* Change "ONNX" from "(hoped for)" to "(experimental)" and apply the
same "(experimental)" to a few other targets
diff --git a/docs/website/mkdocs.yml b/docs/website/mkdocs.yml
index 988fd58..f90dbd4 100644
--- a/docs/website/mkdocs.yml
+++ b/docs/website/mkdocs.yml
@@ -127,10 +127,10 @@
       - "guides/index.md"
       - "ML frameworks":
           - "guides/ml-frameworks/index.md"
-          - TensorFlow: "guides/ml-frameworks/tensorflow.md"
-          - TensorFlow Lite: "guides/ml-frameworks/tflite.md"
           - JAX: "guides/ml-frameworks/jax.md"
           - PyTorch: "guides/ml-frameworks/pytorch.md"
+          - TensorFlow: "guides/ml-frameworks/tensorflow.md"
+          - TensorFlow Lite: "guides/ml-frameworks/tflite.md"
       - "Deployment configurations":
           - "guides/deployment-configurations/index.md"
           - CPU: "guides/deployment-configurations/cpu.md"