lib/options: add mdDoc support to mkEnableOption

lib/options.nix

@@ -95,7 +95,10 @@ rec {
     name: mkOption {
     default = false;
     example = true;
-    description = "Whether to enable ${name}.";
+    description =
+      if name ? _type && name._type == "mdDoc"
+      then lib.mdDoc "Whether to enable ${name.text}."
+      else "Whether to enable ${name}.";
     type = lib.types.bool;
   };