emkRedundantOption: escape backslashes, leave escaping newlines until MD generation

flake.nix

@@ -55,7 +55,7 @@
 
     mkRedundantOption = name: value: attrs: lib.mkOption {
       inherit (attrs) type default;
-      description = "${attrs.description}\n\n<div class=\"admonition-warning\"><p class=\"admonition-title\">::before\nRedundant</p><p>${mkRedundantOptionDescription name value}</p></div>";
+      description = "${attrs.description}\\n\\n<div class=\"admonition-warning\"><p class=\"admonition-title\">::before\\nRedundant</p><p>${mkRedundantOptionDescription name value}</p></div>";
     };
   };
 }