apparmor: fix typo in comment; improve formatting

(#158630)
* apparmor: Fix typo in comment

* apparmor: Formatting

- Normal line length
- Idiomatic Nix
- More clearly separate “code”

pkgs/os-specific/linux/apparmor/default.nix

@@ -304,10 +304,10 @@ let
     meta = apparmor-meta "kernel patches";
   };
 
-  # Generate generic AppArmor rules in a file,
-  # from the closure of given rootPaths.
-  # To be included in an AppArmor profile like so:
-  # include "$(apparmorRulesFromClosure {} [pkgs.hello]}"
+  # Generate generic AppArmor rules in a file, from the closure of given
+  # rootPaths. To be included in an AppArmor profile like so:
+  #
+  #   include "${apparmorRulesFromClosure { } [ pkgs.hello ]}"
   apparmorRulesFromClosure =
     { # The store path of the derivation is given in $path
       additionalRules ? []