Add initial setup for Central DNS and PXE services using dnsmasq

- Created README.md for Central setup documentation.
- Added dnsmasq configuration files and scripts for setting up DNS and PXE booting.
- Implemented nginx configuration to serve PXE boot assets.
- Developed setup.sh script to automate installation and configuration of dnsmasq and nginx.
- Removed outdated dnsmasq setup guide from documentation.

central-setup/dnsmasq/boot.ipxe

@@ -0,0 +1,5 @@
+!ipxe
+imgfree
+kernel http://{{ (ds "config").cloud.dns.ip }}/amd64/vmlinuz talos.platform=metal console=tty0 init_on_alloc=1 slab_nomerge pti=on consoleblank=0 nvme_core.io_timeout=4294967295 printk.devkmsg=on ima_template=ima-ng ima_appraise=fix ima_hash=sha512 selinux=1 net.ifnames=0
+initrd http://{{ (ds "config").cloud.dns.ip }}/amd64/initramfs.xz
+boot