Update rpm.md

for error "The GPG keys listed for the "grafana" repository are already installed but they are not correct for this package."

docs/sources/installation/rpm.md

@@ -57,8 +57,7 @@ baseurl=https://packagecloud.io/grafana/stable/el/6/$basearch
 repo_gpgcheck=1
 repo_gpgcheck=1
 enabled=1
 enabled=1
 gpgcheck=1
 gpgcheck=1
-gpgkey=https://packagecloud.io/gpg.key
-https://grafanarel.s3.amazonaws.com/RPM-GPG-KEY-grafana
+gpgkey=https://packagecloud.io/gpg.key https://grafanarel.s3.amazonaws.com/RPM-GPG-KEY-grafana
 sslverify=1
 sslverify=1
 sslcacert=/etc/pki/tls/certs/ca-bundle.crt
 sslcacert=/etc/pki/tls/certs/ca-bundle.crt
 ```
 ```