website: Add link for v22.1 Doxygen

To be incorporated into the gem5 website for the v22.1 release of gem5.

Change-Id: I72f224fc1c5a9f54c9d7108064f9f0cc6b64119e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/66911
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby Bruce <bbruce@ucdavis.edu>
1 file changed