False information about what is supported

it's [mentioned CentOS 7+](https://github.com/frappe/bench#easy-install-script)

> Note: This script works only on GNU/Linux based server distributions, and has been designed and tested to work on Ubuntu 16.04+, CentOS 7+, and Debian-based systems.

while when we run the easy setup on CentOS 8 (which is7+1 :P)
it require CentOS7

related: https://github.com/frappe/bench/issues/994

the same misleading happen with Ubuntu 16.04+ or 20.04
related: https://github.com/frappe/bench/issues/997 https://github.com/frappe/bench/issues/989

also apparently the easy-install-script has been design and tested
so why this kind of error: https://github.com/frappe/easy_install/issues/31 ??

Start by reviewing the easy-install-script documentation and the CentOS/Ubuntu support claims, then compare them with the installer behavior described in the issue and the linked reports. Done should mean the stated supported versions match verified installer behavior, or the unsupported versions and resulting errors are clearly documented.

Written by the indexing model from the issue text.