docs: add generic dotfile update guide

[alexsmolya]

Fixes #623

Summary

• Add a reusable Configuration guide for comparing CachyOS settings-package defaults in /etc/skel with personal dotfiles using Meld.
• Cover file and directory comparisons, recursive comparison caveats, hiding New files, and selective review/merging.
• Link the existing Hyprland migration page to the generic workflow and retain its Hyprland-specific migration details.

Validation

• Markdown/frontmatter checks passed.
• Internal-link and anchor checks passed.
• git diff --check passed.
• Full wiki build was not run because bun is not installed in the environment.