Documentation/process/embargoed-hardware-issues: Microsoft ambassador

Add Sasha Levin as Microsoft's process ambassador.

Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Link: https://lore.kernel.org/r/20190906095852.23568-1-sashal@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>