better readme
diff --git a/README.md b/README.md
index 47149ce..5b62a6c 100644
--- a/README.md
+++ b/README.md
@@ -302,8 +302,9 @@
return greet + " " + greet + "!";
});
env.render("{{ double-greetings }}", data); // "Hello Hello!"
-
-// You can also add a callback without return variable, e.g. for debugging:
+```
+You can also add a void callback without return variable, e.g. for debugging:
+```.cpp
env.add_void_callback("log", 1, [greet](Arguments args) {
std::cout << "logging: " << args[0] << std::endl;
});
