Linux packages: Added an instruction for yum/dnf to mark the repos as hotfixes. This fixes an issue with RHEL8/CentOS8 where the concept of modules was introduced. If a package with the same name exists both in a modular and traditional repos, the modular one will always have a higher priority. Marking our repository configuration as a hotfix overrides this behavior.

<!--
  Copyright (C) Igor Sysoev
  Copyright (C) Nginx, Inc.
  -->

X:stylesheet {

X:param VERSION = "'development'";

X:output method="text";

X:template = "/versions" { !! "download[@tag=$VERSION][1]/item[1]/@ver"; };

}