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>
diff --git a/_data/documentation.yml b/_data/documentation.yml
index b3f10b2..5087db9 100755
--- a/_data/documentation.yml
+++ b/_data/documentation.yml
@@ -62,6 +62,8 @@
           url: http://doxygen.gem5.org/release/v22-0-0-0/index.html
         - page: v22.0.0.1
           url: http://doxygen.gem5.org/release/v22-0-0-1/index.html
+        - page: v22.1.0.0
+          url: http://doxygen.gem5.org/release/v22-1-0-0/index.html
 
     - title: gem5 standard library
       id: gem5-standard-library