BUG #15441: Repo package are missing for CentOS

The following bug has been logged on the website:

Bug reference:      15441
Logged by:          - -
Email address:      frank.buettner@mdc-berlin.de
PostgreSQL version: 11.0
Operating system:   CentOS
Description:        

Using https://yum.postgresql.org/repopackages.php#pg11 to install PostgreSQL
will fail, because the base package "pgdg-centos11-11-2.noarch.rpm" are not
found on the server.
https://download.postgresql.org/pub/repos/yum/11/redhat/rhel-7-x86_64/
Will only contains the pgdg-* packages for RHEL.
The packages for CentOS, Oracle Linux and Scientific Linux are missing.