General documentation updates epic issue

[xmfcx]

• Populate https://autowarefoundation.github.io/autoware-documentation/main/simulation-evaluation/ with architecture taskforce private document (make it public here?)
• Add 2.0 Architecture docs
• Mention privately owned vehicle repos more openly.

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• feat: add reference design section #525 simplify this, remove outdated info and merge
  • it should have clear links to PoV(privately owned vehicles) and LSA(low speed autonomy) ref design pages. Also include explanation.
• Improve concepts page, some initial work done in feat: restructure docs #702
  • Done in feat: split and improve concepts and rename versioning pages #734

[xmfcx]

I'll add this separately:

First of all, finalize these open PRs. Only 4 actual old PRs left, the other 2 are part of tasks above.
I updated improved and merged like 30 open PRs last week, we just need to focus and finish the backlog. This is just documentation, where the risks of changing things are much lower and we can move faster here.

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Everything has been cleaned up ✨🍃🧹🍃✨