Deprecate /workflow index page

doc/workflow/README.md

 ---
-comments: false
+redirect_to: '../README.md'
 ---
 
-# Workflow (Deprecated)
-
-This page was deprecated, with all content previously stored under the `/workflow` path moved
-to other locations in the documentation site, organized by topic. You can use the search
-box to find the content you are looking for, browse the main [GitLab Documentation page](../README.md),
-or view the [issue that deprecated this page](https://gitlab.com/gitlab-org/gitlab/issues/32940)
-for more details.
+This document was moved to [another location](../README.md).