util: fix code block language in docs

Without {.xml}, Doxygen interprets the code as C. See [1] for
details.

[1]: https://www.doxygen.nl/manual/commands.html#cmdcode

Signed-off-by: Simon Ser <contact@emersion.fr>

diff --git a/src/wayland-util.h b/src/wayland-util.h
index 7997778..18c512e 100644 (file)
--- a/src/wayland-util.h
+++ b/src/wayland-util.h
@@ -182,7 +182,7 @@ struct wl_message {
  * For example, consider a protocol interface `foo`, marked as version `1`, with
  * two requests and one event.
  *
- * \code
+ * \code{.xml}
  * <interface name="foo" version="1">
  *   <request name="a"></request>
  *   <request name="b"></request>