docs: proxmox installation steps and kubeconfig command - #701

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-go@v5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

heading should be sentence case; lowercase "Controller" (or add it to exceptions.txt if it's a proper noun)

heading directly follows the heading on line 330; add at least one sentence between them

heading directly follows the heading on line 23; add at least one sentence between them