Add roadmap to docs

[skasberger]

Requirements:

• Revisioning:
  • Version
  • Creator
  • Creation data
• Goals
• Motivation
• Content
  • Community
  • Development
  • Governance

Plan

• Research other roadmaps
  • https://www.aha.io/roadmapping/guide/product-roadmap
  • https://www.productplan.com/learn/building-your-first-product-roadmap/
  • https://www.shopify.com/partners/blog/product-roadmap
  • https://mozillascience.github.io/working-open-workshop/roadmapping/
  • https://towardsdatascience.com/getting-started-with-open-source-roadmap-35c6f76682b7
  • https://opensource.guide/de/starting-a-project/

[pdurbin]

As discussed during the 2024-02-14 meeting of the pyDataverse working group, we are closing old milestones in favor of a new project board at https://github.com/orgs/gdcc/projects/1 and removing issues (like this one) from those old milestones. Please feel free to join the working group! You can find us at https://py.gdcc.io and https://dataverse.zulipchat.com/#narrow/stream/377090-python