website: Added GCN3 page

Change-Id: I448d69a6b2df8e4db1202256f9a47509fe85866c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/29332
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: Jason Lowe-Power <power.jg@gmail.com>
2 files changed