Update release-8-3.md

[Jarli01]

Outlines the steps required to close port 80 on a per host basis if the pool wide option doesn't address the issue.

Before submitting the pull request, you must agree with the following statements by checking both boxes with a 'x'.

• [ x ] "I accept that my contribution is placed under the CC BY-SA 2.0 license [1]."
• [ x] "My contribution complies with the Developer Certificate of Origin [2]."

[1] https://creativecommons.org/licenses/by-sa/2.0/
[2] https://docs.xcp-ng.org/project/contributing/#developer-certificate-of-origin-dco

[stormi]

I don't understand "If the pool wide settings don't close port 80". It sounds like it's random, it may or may not work. Do we have more information about this?

[stormi]

Ping @Jarli01