Tracking: Complete the v4.0.0 release docs milestone

[FaithKovi]

Summary

The v4.0.0 release docs milestone is 5 months overdue (original due date: November 10, 2025) and sits at 66% completion. Helm v4.1.1 has shipped, the docs are live at helm.sh/docs, and users are actively adopting Helm 4, but three issues remain open, and several pages still carry "not yet updated for Helm 4" warnings.

This issue tracks the remaining work needed to close the milestone.

Current state

Closed (6 of 9)

#	Issue
#1862	Audit the v3 docs for v4 updates
#1845	Update path of v3 docs from /3/ to /v3/
#1887	Add Helm 4 migration guide
#1888	Update "The History of the Project" with Helm 4
#1886	Update Contributing doc for CommonMark/MDX

Open (3 of 9)

#	Issue
#1889	Document new Wasm plugin system (Partially done)
#1863	Add a Helm overview page to the docs
#1864	Update information architecture for v4 docs. Depends on #1862 (closed).

Closing criteria

The milestone can be closed when:

• Document new Wasm plugin system #1889 remaining gaps are completed (migration guide, legacy
  page move, Overview enhancements)
• Add a Helm overview page to the docs #1863 is completed
• Update the information architecture for the v4 docs #1864 is completed
• No pages in the docs/ directory (v4) carry the generic
  "not yet updated for Helm 4" warning without a clear plan