Add CHANGES and release notes for [GL #2295]

CHANGES

@@ -1,3 +1,9 @@
+5966.	[func]		You can now specify if a server must return a DNS
+			COOKIE before accepting the response over UDP.
+			[GL #2295]
+
+			server <prefix> { require-cookie <yes_or_no>; };
+
 5965.	[cleanup]	Move the duplicated ASCII case conversion tables to
 			isc_ascii where they can be shared, and replace the
 			various hot-path tolower() loops with calls to new

doc/notes/notes-current.rst

@@ -27,6 +27,12 @@ New Features
 
 - None.
 
+- A new configuration option ``require-cookie`` has been introduced, it
+  specifies if there should be a DNS COOKIE in the response for a given
+  prefix and if not named falls back to TCP.  This is useful if you know
+  a given server support DNS COOKIE.  It can also be used to force all
+  non DNS COOKIE responses to fall back to TCP.  :gl:`#2295`
+
 Removed Features
 ~~~~~~~~~~~~~~~~