Rewrite a couple of lines in the TF XLA doc
This PR makes a quick edit at the top of the TF XLA doc to clarify that for training/inference you can just pass `jit_compile` to `model.compile()`! (cc @sayakpaul )
(Going to assume this one is small enough to merge without @sgugger approval, but feel free to yell at me if it wasn't!)<|||||>_The documentation is not available anymore as the PR was closed or merged._