Redirect development page

Why is this change being made?

This MR removes the old duplicated development and adds a redirect to the new location on docs.gitlab.com. This is a follow up to !122807 (diffs) that had updated the link but forgot the redirect and page removal.

Author Checklist

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
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