Extra Step for Installing AppProtect on Rocky 9

[jhuttley-F5-com]

On following these instructions

https://docs.nginx.com/waf/install/virtual-environment/#rhel--rocky-linux-9

AppProtect does not install because it does not pull the dependencies

Resolution:
Add one more step

sudo dnf config-manager --set-enabled crb

[mjang]

As this issue came from a customer ticket, I think it's a candidate for a p1.

Acceptance criteria: I think we should also check this for RHEL 8 installs, specifically https://docs.nginx.com/waf/install/virtual-environment/#oracle-linux--rhel--rocky-linux-8

[JTorreG]

other RHEL distros might need this change too

[ADubhlaoich]

No-op on other RHEL distros: addressed in a current PR.