docs: improve diagnostics user journey - #131

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: pkgjs/request-codeowner-review@d39b61c5e1399655dce6287b3b119af93dee235a. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/