website: Add v22.0.0.0 doxygen

Change-Id: I12b728519d2657dd296019f9138a8cf990393965
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/60513
Tested-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
diff --git a/_data/documentation.yml b/_data/documentation.yml
index 215a320..2d24b87 100755
--- a/_data/documentation.yml
+++ b/_data/documentation.yml
@@ -58,6 +58,8 @@
           url: http://doxygen.gem5.org/release/v21-2-1-0/index.html
         - page: v21.2.1.1
           url: http://doxygen.gem5.org/release/v21-2-1-1/index.html
+        - page: v22.0.0.0
+          url: http://doxygen.gem5.org/release/v22-0-0-0/index.html
 
     - title: gem5 standard library
       id: gem5-standard-library