Create a latest Product Development Flow with minimal change management

Why is this change being made?

Provide a latest document to iterate on the product development flow with minimal change management.

Proposed implementation, see !62930 (merged)

1. Create a separate file product-development-flow/product-development-latest.html.md
2. Work on changes on that file
3. Merge into product-development-flow/index.html.md on 17th of month
4. Announce changes to team in release post if required

Closes #9055 (closed)

Author Checklist

• Provided a concise title for the MR
• Added a description to this MR explaining the reasons for the proposed change, per [say-why-not-just-what][transparency]
• Assign this change to the correct DRI
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to your manager.
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in [#mr-buddies][mr-buddies-slack].
  • If the changes relate to any part of the project other than updates to content and/or data files please make sure to ping @gl-static-site-editor in a comment for a review and merge. For example changes to .gitlab-ci.yml, JavaScript/CSS/Ruby code or the layout files.