clarify C8 Upstream->CERN instructions

docs/centos8/docs/install.md

@@ -32,9 +32,9 @@ The following methods are currently available to install CentOS 8
     priority=5
     gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-kojiv2
     EOF
+    curl -o /etc/pki/rpm-gpg/RPM-GPG-KEY-kojiv2 https://linux.web.cern.ch/keys/RPM-GPG-KEY-kojiv2
+    rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-kojiv2
     dnf --repo cern update centos-release
     ```
 
-    Download [RPM-GPG-KEY-kojiv2](/keys/RPM-GPG-KEY-kojiv2) to pass the GPG checks, and then run `dnf clean all && dnf reinstall centos-release`.
-
 For a detailed installation of a Linux Desktop, check the [step by step guide](/centos8/docs/stepbystep)