[OpenMP][docs] Update OpenMP 6.0 OMP_AVAILABLE_DEVICES status (#162440)

The trait support being implemented for OMP_DEFAULT_DEVICES can also be
used for OMP_AVAILABLE_DEVICES, which makes it reasonable to wait to
avoid duplicate effort.

Author: ro-i

clang/docs/OpenMPSupport.rst

@@ -548,7 +548,7 @@ implementation.
 +-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+
 | Increment between places for OMP_PLACES                     | :none:`unclaimed`         | :none:`unclaimed`         |                                                                          |
 +-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+
-| OMP_AVAILABLE_DEVICES envirable                             | :none:`unclaimed`         | :none:`unclaimed`         |                                                                          |
+| OMP_AVAILABLE_DEVICES envirable                             | :none:`unclaimed`         | :none:`unclaimed`         | (should wait for "Traits for default device envirable" being done)       |
 +-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+
 | Traits for default device envirable                         | :part:`in progress`       | :none:`unclaimed`         | ro-i                                                                     |
 +-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+