website: Add Doxygen link for v21.1.0.2

Change-Id: I9d1c08fd8859cad525b80dd2cd5193b927ea6deb
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/50768
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby R. Bruce <bbruce@ucdavis.edu>
diff --git a/_data/documentation.yml b/_data/documentation.yml
index 59d3478..f414506 100755
--- a/_data/documentation.yml
+++ b/_data/documentation.yml
@@ -50,6 +50,8 @@
           url: http://doxygen.gem5.org/release/v21-1-0-0/index.html
         - page: v21.1.0.1
           url: http://doxygen.gem5.org/release/v21-1-0-1/index.html
+        - page: v21.1.0.2
+          url: http://doxygen.gem5.org/release/v21-1-0-2/index.html
 
     - title: gem5 Resources
       id: gem5_resources