ext: Add DRAMSys integration instructions

Add instructions to add the DRAMSys memory simulator
to gem5 in the ext/ directory.
The provided SConscript file compiles DRAMSys.

Change-Id: If5c723db61a3151c9155190f968c66927d7bfaa3
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/62911
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
2 files changed