docs/Homebrew-on-Linux: update dnf5 syntax, centos/rhel section

Tested on Fedora 42 and CentOS Stream/RHEL 10 (latest for all).

Note: Fedora 42 uses dnf5 while CentOS Stream/RHEL 10 use dnf4

See:
- https://github.com/Homebrew/install/pull/894
- https://github.com/Homebrew/install/blob/0fd28f83c8a60d8a8fc1d15a1f023d01aa4b7de5/install.sh#L1133