resources: Updated URL to `stable` instead of `master`

Change-Id: Ie9e29bdf991d1b8efef73e053f760f9adedc63d7
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-resources/+/35458
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby R. Bruce <bbruce@ucdavis.edu>
1 file changed
tree: 794201e8ac5479fabd1f2affe5cb8555e278c15f
  1. README.md
  2. src/