Added Multi-Host TPU tutorial

Author: vfdev-5

docs/source/index.rst

@@ -42,6 +42,7 @@ Tutorials
    learn/xla-examples
    learn/xla-profiling
    learn/xla-advanced
+   learn/xla-multi-host-tpu
 
 .. toctree::
    :glob:
@@ -50,7 +51,7 @@ Tutorials
 
    accelerators/tpu
    tutorials/precision_tutorial
-   perf/spmd_basic      
+   perf/spmd_basic
    perf/spmd_advanced
    perf/spmd_distributed_checkpoint
    features/torch_distributed