fix RPM package repository url (#292)

Co-authored-by: dahn <daan.hoogland@gmail.com>

Author: soubinan

source/installguide/management-server/_pkg_repo.rst

@@ -51,11 +51,13 @@ To add the CloudStack repository, create
 ``/etc/yum.repos.d/cloudstack.repo`` and insert the following
 information.
 
+In the case of RHEL being used, you can replace 'centos' by 'rhel' in the value of baseurl
+
 .. parsed-literal::
 
    [cloudstack]
    name=cloudstack
-   baseurl=http://download.cloudstack.org/centos$releasever/|version|/
+   baseurl=http://download.cloudstack.org/centos/$releasever/|version|/
    enabled=1
    gpgcheck=0