Fix a few docs blocks

src/hb-ot-layout.cc

diff --git a/src/hb-ot-layout.cc b/src/hb-ot-layout.cc
index 3d4ee16..b0257f6 100644
--- a/src/hb-ot-layout.cc
+++ b/src/hb-ot-layout.cc
@@ -130,6 +130,8 @@
 }
 
 /**
+ * hb_ot_layout_get_glyph_class:
+ *
  * Since: 0.9.7
  **/
 hb_ot_layout_glyph_class_t
@@ -140,6 +142,8 @@
 }
 
 /**
+ * hb_ot_layout_get_glyphs_in_class:
+ *
  * Since: 0.9.7
  **/
 void
@@ -365,6 +369,8 @@
 }
 
 /**
+ * hb_ot_layout_language_get_required_feature:
+ *
  * Since: 0.9.30
  **/
 hb_bool_t