Release v2.59.0 (#7840)

Author: yufeih

RELEASENOTE.md

@@ -1,6 +1,12 @@
-Version Notes (Current Version: v2.58.9)
+Version Notes (Current Version: v2.59.0)
 =======================================
 
+v2.59.0
+-----------
+1. Upgrade markdig to 2.26.0. (#7701)
+2. Allow custom markdig extensions. (#3387)
+3. Only show public interfaces in generated syntax. (#3154)
+
 v2.58.9
 -----------
 1. Fix invalid Github release asset. (#7690)