Support for Korora distrib (korora-release-21-2.noarch)

[guizmaii]

Korora is just a pre-config Fedora (and a great distrib !)

~ ❯ curl --silent --location https://rpm.nodesource.com/setup | bash -

## Inspecting system...

+ rpm -q --whatprovides redhat-release || rpm -q --whatprovides centos-release || rpm -q --whatprovides cloudlinux-release
+ uname -m

## You don't appear to be running a supported version of Enterprise Linux. Please contact NodeSource at https://github.com/nodesource/distributions/issues if you think this is incorrect or would like your architecture to be considered for support. Include your 'distribution package' name: korora-release-21-2.noarch. 

[perguth]

👍 Or more recent: korora-release-22-1.noarch

[retrohacker]

Adding distribution request to the README.md,

Will land in #308