docs/Homebrew-on-Linux: update instructions for Fedora-based distros

[xty]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew typecheck with your changes locally?
• Have you successfully run brew tests with your changes locally?

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This PR introduces a number of changes to Homebrew-on-Linux.md regarding instructions for Fedora-based distributions:

• Change CentOS to CentOS Stream
  • CentOS has been discontinued, and CentOS Stream now serves as the downstream of Fedora and the upstream of RHEL.
• Change "Red Hat" to RHEL
  • Red Hat Enterprise Linux is commonly and officially referred to as RHEL, not "Red Hat". The former Red Hat Linux has also been discontinued.
• Change yum to dnf
  • dnf has been the default package manager on Fedora for over 10 years (since Fedora 22) and on RHEL for over 6 years (since RHEL 8).
  • More importantly, yum groupinstall 'Development Tools' no longer works on Fedora since its adoption of DNF5.
  • This change also aligns with the current installation script, which prioritises dnf over yum.
• Remove git from the second command
  • git is already included in the Development Tools group.

[p-linnane]

Makes sense to me. Thanks @xty!