diff --git a/docs/service-implementation-guide.md b/docs/service-implementation-guide.md
index 735caef..2ecdc8b 100644
--- a/docs/service-implementation-guide.md
+++ b/docs/service-implementation-guide.md
@@ -381,14 +381,16 @@ source: @OPTIONS_JSON@
 
 Note: Replace `servicename` with your actual service name (e.g., `nzbget`, `jellyfin`).
 
-For the `@OPTIONS_JSON@` to work, the following snippet must be added
-in the `docs/default.nix` file.
+For the `@OPTIONS_JSON@` to work, a line must be added
+in the `flake.nix` file:
 
 ```nix
-substituteInPlace ./modules/services/servicename/docs/default.md \
-  --replace \
-    '@OPTIONS_JSON@' \
-   ${individualModuleOptionsDocs [ ../modules/services/servicename.nix ]}/share/doc/nixos/options.json
+packages.manualHtml = pkgs.callPackage ./docs {
+  modules = {
+    "blocks/authelia" = ./modules/blocks/authelia.nix;
+    // Add line and keep in alphabetical order.
+  };
+};
 ```
 
 ### 7. Update Redirects Automatically {#update-redirects-automatically}