Hi
There is no need for you to give me credit and it just distracts people from your tutorial
(thanks but be free to drop that text ) 
Simply write at the beginning something like:
If you have set Cloudflare cache settings to “cache everything”
then it is in your interest to isolate sitemap.xml from that rule
so a new fresh version is served rather than an outdated one (cached).
btw. one small typo yourdoamin.tld