Add linux-sched-ext to CachyOS repo

[sirlucjan]

Along with the name change, sched-ext/scx-packaging-arch@2c48384 kernel went into the CachyOS repo. Pull Request includes a change to the installation instructions. Now it is no longer necessary to put the kernel in the repo on Github, it will be available in CachyOS and updated with each release.

❯ pacman -Ss linux-sched-ext
cachyos/linux-sched-ext 6.7.1.scx1-2
    The Linux kernel and modules
cachyos/linux-sched-ext-docs 6.7.1.scx1-2
    Documentation for the Linux kernel
cachyos/linux-sched-ext-git 6.7.0.r1236012.g6eb6c92567b1-5
    The Linux Kernel based on the sched_ext branch kernel and modules
cachyos/linux-sched-ext-git-headers 6.7.0.r1236012.g6eb6c92567b1-5
    Headers and scripts for building modules for the Linux Kernel based on the sched_ext branch kernel
cachyos/linux-sched-ext-git-scheduler 6.6.0.r1216283.g41728bbcdd6c-1
    Schedulers for Linux Kernel based on the sched_ext branch kernel
cachyos/linux-sched-ext-headers 6.7.1.scx1-2
    Headers and scripts for building modules for the Linux kernel

[Byte-Lab]

LGTM, thanks. Will let @htejun look as well given that he added the arch custom package.