[docs] Missing param docs
diff --git a/src/hb-font.cc b/src/hb-font.cc
index 378c69b..a836185 100644
--- a/src/hb-font.cc
+++ b/src/hb-font.cc
@@ -1834,7 +1834,7 @@
/**
* hb_font_set_funcs:
* @font: #hb_font_t to work upon
- * @klass: (closure font_data) (destroy destroy) (scope notified):
+ * @klass: (closure font_data) (destroy destroy) (scope notified): The font-functions structure.
* @font_data: Data to attach to @font
* @destroy: (nullable): The function to call when @font_data is not needed anymore
*
