Merge branch 'jeremy-master-patch-16204' into 'master'

Added available date for Subgroups (GitLab 9.0)

See merge request gitlab-com/www-gitlab-com!37013

data/categories.yml

@@ -101,7 +101,7 @@ subgroups:
   description: "Organize your projects and restrict access to controlled resources."
   roi: false
   marketing: true
-  available: 
+  available: 2017-03-22
   viable: 
   complete: 2019-01-01
   lovable: 2020-12-31