The new description should give more clear understanding of when to
edit the option.

Motivation for this change

I used NixOS to set up a DNS server that is authoritative for certain zones. The description of the cacheNetworks option made me think I needed to set it to "any" to allow people to query the zone I set up. Reading the source of the module would have clarified my understanding, but at the time I just read the description and thought little of it. Later I discovered I was getting tons of DNS requests and presumably being used for a DNS amplification attack or similar. I have fixed the problem now, but I would like the option to have a clearer description so others don't make the same mistake I did.

I'm not tied to the prose I wrote, but I would like to see the description expanded to clarify the issue.

Things done

I only changed a string. I only tested it as far as ensuring that it didn't cause a syntax error.

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @peti @globin