set .cpp in readme
diff --git a/README.md b/README.md
index 376bfb7..a005a73 100644
--- a/README.md
+++ b/README.md
@@ -185,7 +185,7 @@
render("{% include \"footer.html\" %}", data);
```
If a corresponding template could not be found in the file system, the *include callback* is called:
-```
+```.cpp
// The callback takes the current path and the wanted include name and returns a template
env.set_include_callback([&env](const std::string& path, const std::string& name) {
return env.parse("Hello {{ name }} from " + name);
