Add a note about building AMI to security doc

doc/release/security.md

@@ -18,6 +18,7 @@ Please report suspected security vulnerabilities in private to <support@gitlab.c
 1. Do the steps from [patch release document](doc/release/patch.md), starting with "Create an issue on private GitLab development server"
 1. The MR with the security fix should get a 'security' label and be assigned to the release manager
 1. Build the package for GitLab.com and do a deploy
+1. [Create new AMIs](https://dev.gitlab.org/gitlab/AMI/blob/master/README.md)
 1. Create feature branches for the blog post on GitLab.com and link them from the code branch
 1. Merge and publish the blog posts
 1. Send tweets about the release from `@gitlabhq`