Documentation/process: Add embargoed HW contact for Ampere Computing

Add Darren Hart as Ampere Computing's ambassador for the embargoed
hardware issues process.
Signed-off-by: Darren Hart <darren@os.amperecomputing.com>
Link: https://lore.kernel.org/r/2e36a8e925bc958928b4afa189b2f876c392831b.1650995848.git.darren@os.amperecomputing.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/process/embargoed-hardware-issues.rst

@@ -245,6 +245,7 @@ an involved disclosed party. The current ambassadors list:
 
   ============= ========================================================
   AMD		Tom Lendacky <tom.lendacky@amd.com>
+  Ampere	Darren Hart <darren@os.amperecomputing.com>
   ARM		Grant Likely <grant.likely@arm.com>
   IBM Power	Anton Blanchard <anton@linux.ibm.com>
   IBM Z		Christian Borntraeger <borntraeger@de.ibm.com>