Add CHANGES for idn2 support

(cherry picked from commit 8f44ef7d)

CHANGES

+4915.	[func]		Implement IDNA2008 support in dig by adding support
+			for libidn2.  New dig option +idnin has been added,
+			which allows to process invalid domain names much
+			like dig without IDN support.  libidn2 version 2.0
+			or higher is needed for +idnout enabled by default.
+
 4914.	[bug]		A bug in zone database reference counting could lead to
 			a crash when multiple versions of a slave zone were
 			transferred from a master in close succession.