Update table of contents in README.md (#5045)

### PR Description
Adding and fixing some links in the table of contents of the README.

Author: stefanhaller

README.md

@@ -95,12 +95,16 @@ If you're a mere mortal like me and you're tired of hearing how powerful git is
   - [MacPorts](#macports)
   - [Void Linux](#void-linux)
   - [Scoop (Windows)](#scoop-windows)
+  - [gah (Linux and Mac OS)](#gah-linux-and-mac-os)
   - [Arch Linux](#arch-linux)
-  - [Fedora and RHEL](#fedora-and-rhel)
+  - [Fedora / Amazon Linux 2023 / CentOS Stream](#fedora--amazon-linux-2023--centos-stream)
   - [Solus Linux](#solus-linux)
   - [Debian and Ubuntu](#debian-and-ubuntu)
   - [Funtoo Linux](#funtoo-linux)
   - [Gentoo Linux](#gentoo-linux)
+  - [openSUSE](#opensuse)
+  - [NixOS](#nixos)
+  - [Flox](#flox)
   - [FreeBSD](#freebsd)
   - [Termux](#termux)
   - [Conda](#conda)