[meta] New API, hb_ot_metadata_reference_entry for fetching meta entries

docs/harfbuzz-sections.txt

diff --git a/docs/harfbuzz-sections.txt b/docs/harfbuzz-sections.txt
index 43fd761..888859e 100644
--- a/docs/harfbuzz-sections.txt
+++ b/docs/harfbuzz-sections.txt
@@ -608,6 +608,12 @@
 </SECTION>
 
 <SECTION>
+<FILE>hb-ot-metadata</FILE>
+hb_ot_metadata_reference_entry
+hb_ot_metadata_t
+</SECTION>
+
+<SECTION>
 <FILE>hb-ot-metrics</FILE>
 hb_ot_metrics_t
 hb_ot_metrics_get_position