Address Greg's comment on ambiguous language for HSOC_020

Signed-off-by: Andrei Warkentin <andrei.warkentin@intel.com>

server_platform_requirements.adoc

@@ -12,7 +12,7 @@ A RISC-V server platform is based on a RISC-V SoC with RISC-V application proces
 2+| _The Server SoC specification is still under construction. This specification should
     be updated once the specification versioning info is finalized._
 | HSOC_020  | All peripherals that are intended for assignment to a VM or a user space device driver must be
-based on PCIe.
+PCIe devices or be compliant to rules for SoC-integrated PCIe devices (cite:[ServerSoC, Section 2.5.11).
 |===
 
 === Peripherals