[Distributed] update table in docs (pytorch#165009)

Fixes pytorch#162248

Pull Request resolved: pytorch#165009
Approved by: https://github.com/ezyang

Author: stmcgovern

docs/source/distributed.md

@@ -51,7 +51,7 @@ MPI supports CUDA only if the implementation used to build PyTorch supports it.
 +----------------+-----+-----+-----+-----+-----+-----+-----+-----+
 | reduce_scatter | ✓   | ✓   | ✘   | ✘   | ✘   | ✓   | ✘   | ✓   |
 +----------------+-----+-----+-----+-----+-----+-----+-----+-----+
-| all_to_all     | ✓   | ✓   | ✓   | ?   | ✘   | ✓   | ✘   | ✓   |
+| all_to_all     | ✘   | ✘   | ✓   | ?   | ✘   | ✓   | ✘   | ✓   |
 +----------------+-----+-----+-----+-----+-----+-----+-----+-----+
 | barrier        | ✓   | ✘   | ✓   | ?   | ✘   | ✓   | ✘   | ✓   |
 +----------------+-----+-----+-----+-----+-----+-----+-----+-----+