Modify All-To-All doc (#896)

* Modify All-To-All doc

* Update nccl.h.in

* update unit-tests

---------

Co-authored-by: gilbertlee-amd <44450918+gilbertlee-amd@users.noreply.github.com>

[ROCm/rccl commit: c1f57a7041]

projects/rccl/test/AllToAllTests.cpp

@@ -3,6 +3,9 @@
  *
  * See LICENSE.txt for license information
  ************************************************************************/
+
+ // Note: InPlace is not supported for All-To-All
+
 #include "TestBed.hpp"
 
 namespace RcclUnitTesting