Fix misleading comments about `home.file` linking behavior

This PR **clarifies comments** around `home.file` usage in Home Manager configuration. The previous comments described the behavior as “directly linking local files/directories into `$HOME`”, which is **not accurate from an implementation perspective**. In reality: * Files and directories specified via `source = ./...` are first **imported into the Nix store** * Home Manager then creates **symbolic links from `$HOME` to the corresponding Nix store paths** * No direct symlink to the local configuration directory is ever created This PR **only updates comments** to reflect the actual Nix/Home Manager model more precisely. There are **no functional or behavioral changes**.