[master] improve EDNS doc

3721.	[doc]		Improved doucmentation of the EDNS processing
			enhancements introduced in change #3593. [RT #35275]

CHANGES

@@ -1,3 +1,6 @@
+3721.	[doc]		Improved doucmentation of the EDNS processing
+			enhancements introduced in change #3593. [RT #35275]
+
 3720.	[bug]		Address compiler warnings. [RT #35261]
 
 3719.	[bug]		Address memory leak in in peer.c. [RT #35255]

EDNS-9.10

@@ -1,33 +0,0 @@
-Copyright (C) 2013  Internet Systems Consortium, Inc. ("ISC")
-See COPYRIGHT in the source root or http://isc.org/copyright.html for terms.
-
-			EDNS in BIND 9.10
-
-The EDNS code in BIND 9.10 records successful plain and EDNS query
-counts as well at timeouts for plain DNS and EDNS queries at various
-EDNS buffer sizes: 4096, 1432, 1232 and 512 for each server named
-talks to.  A EDNS timeout for a lower buffer size is also counted
-against higher buffer sizes.  These are held in 8 bit counters and
-are shifted on overflow of any counter.  This will result in false
-positives due to transitory network problems to be removed from the
-history.
-
-The buffer sizes of 1432 and 1232 are choosen to allow for a IPv4/IPv6
-encapsulated UDP message to be sent without fragmentation at Ethernet
-and IPv6 network mimimum MTU sizes.
-
-Named also records the largest successful EDNS response size seen.
-
-When talking to a new server named will send a EDNS query advertising
-a 512 byte UDP buffer.  This is the most conservative EDNS message
-that can be sent.  If this results in a response with TC=1 being
-sent a larger EDNS buffer size will be used rather than a immediate
-fallback to TCP.
-
-If there are too many timeouts to EDNS queries without a successful EDNS
-query and with successful plain DNS queries named will fallback to using
-plain DNS when taking to a server.  Named will periodically send a EDNS
-query to see if the server now supports EDNS.
-
-When talking to a server using EDNS named will choose a EDNS buffer size
-based on the history of EDNS timeouts at various advertised sizes.