docs: explain restoring an earlier secret version - #595

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@11d5960a326750d5838078e36cf38b85af677262, jetli/wasm-pack-action@0d096b08b4e5a7de8c28de67e11e945404e9eefa. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/