docs: improve .env.example.full reranker and embedding provider documentation - #1073

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: lizheming/github-translate-action@1.1.2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/