Add CentOS installation option to Xinzhou Unicom rack

dnsmasq_xinzhou_unicom.sh

-#!/bin/sh
+#!/bin/bash
+# To install CentOS apache must be installed and server CentOS base
+# root@raspberrypi:/ apt install apache2 -y
+# root@raspberrypi:/ systemctl start httpd
+# root@raspberrypi:/var/www/html# cp -a /root/rapidspace-autoinstall-os/centos-installer/ .
+# root@raspberrypi:/var/www/html# chown pi: -R centos-installer/
+# root@raspberrypi:/var/www/html# wget http://192.168.46.2/centos-installer/media.repo # just check
+
 set -e
 
 SCRIPT_DIR=$(realpath `dirname "$0"`)
@@ -8,6 +15,7 @@ SCRIPT_DIR=$(realpath `dirname "$0"`)
 
 download_debian_10_if_needed
 download_sysrescuecd_if_needed
+download_centos_8_if_needed
 
 #UPDATE THOSE VARIABLES DEPENDING ON YOUR SITE
 MY_IF_NAME=ens9f1
@@ -47,10 +55,14 @@ cat <<EOF
 else unset timeout
 fi
 
-menuentry 'Install Debian' {
+menuentry 'Install Debian 10' {
   linux /debian-installer/amd64/linux vga=788 url=tftp://\$pxe_default_server/preseed_xinzhou_unicom.cfg language=C country=CN keymap=us hostname=${hostname_prefix}\$i domain= --- mitigations=off $common
   initrd /debian-installer/amd64/initrd.gz
 }
+menuentry 'Install CentOS' {
+  linux /centos-installer/images/pxeboot/vmlinuz checksum ip=dhcp inst.text inst.repo=http://\$pxe_default_server/centos-installer/  $common
+  initrd /centos-installer/images/pxeboot/initrd.img
+}
 menuentry 'SystemRescueCd' {
   linux /sysresccd/sysresccd/boot/x86_64/vmlinuz archisobasedir=sysresccd archiso_http_srv=http://\$pxe_default_server:69/sysresccd/ checksum ip=dhcp $common
   initrd /sysresccd/sysresccd/boot/intel_ucode.img /sysresccd/sysresccd/boot/amd_ucode.img /sysresccd/sysresccd/boot/x86_64/sysresccd.img