website: Add v21.0.0.1 Doxygen link

Change-Id: Iacd3c7738ae170ebf84e860fc1f20ee67c89af1d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/60669
Tested-by: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
diff --git a/_data/documentation.yml b/_data/documentation.yml
index 2d24b87..c32e9df 100755
--- a/_data/documentation.yml
+++ b/_data/documentation.yml
@@ -60,6 +60,8 @@
           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
+        - page: v22.0.0.1
+          url: http://doxygen.gem5.org/release/v22-0-0-1/index.html
 
     - title: gem5 standard library
       id: gem5-standard-library