as suggested by jtodd, document the purposes of the CHANGES and UPGRADE files

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@158449 65c4cc65-6c06-0410-ace0-fbb531ad65f3

CHANGES

@@ -1,3 +1,13 @@
+======================================================================
+===
+=== This file documents the new and/or enhanced functionality added in
+=== the Asterisk versions listed below. This file does NOT include
+=== changes in behavior that would not be backwards compatible with
+=== previous versions; for that information see the UPGRADE.txt file
+=== and the other UPGRADE files for older releases.
+===
+======================================================================
+
 ------------------------------------------------------------------------------
 --- Functionality changes from Asterisk 1.6.1 to Asterisk 1.6.2  -------------
 ------------------------------------------------------------------------------

UPGRADE-1.2.txt

@@ -1,10 +1,17 @@
 =========================================================
+===
 === Information for upgrading from Asterisk 1.0 to 1.2
 ===
+=== This file documents all the changes that MUST be taken
+=== into account when upgrading between the Asterisk
+=== versions listed below. These changes may require that
+=== you modify your configuration files, dialplan or (in
+=== some cases) source code if you have your own Asterisk
+=== modules or patches. These files also includes advance
+=== notice of any functionality that has been marked as
+=== 'deprecated' and may be removed in a future release,
+=== along with the suggested replacement functionality.
 ===
-=== UPGRADE-1.2.txt -- Upgrade info for 1.0 to 1.2
-=== UPGRADE-1.4.txt -- Upgrade info for 1.2 to 1.4
-=== UPGRADE.txt     -- Upgrade info for 1.4 to 1.6
 =========================================================
 
 Compiling:

UPGRADE-1.4.txt

@@ -1,10 +1,19 @@
 =========================================================
+===
 === Information for upgrading from Asterisk 1.2 to 1.4
 ===
+=== These files document all the changes that MUST be taken
+=== into account when upgrading between the Asterisk
+=== versions listed below. These changes may require that
+=== you modify your configuration files, dialplan or (in
+=== some cases) source code if you have your own Asterisk
+=== modules or patches. These files also includes advance
+=== notice of any functionality that has been marked as
+=== 'deprecated' and may be removed in a future release,
+=== along with the suggested replacement functionality.
 ===
 === UPGRADE-1.2.txt -- Upgrade info for 1.0 to 1.2
-=== UPGRADE-1.4.txt -- Upgrade info for 1.2 to 1.4
-=== UPGRADE.txt     -- Upgrade info for 1.4 to 1.6
+===
 =========================================================
 
 Build Process (configure script):

UPGRADE-1.6.txt

@@ -1,10 +1,20 @@
 =========================================================
+===
 === Information for upgrading from Asterisk 1.4 to 1.6
 ===
+=== These files document all the changes that MUST be taken
+=== into account when upgrading between the Asterisk
+=== versions listed below. These changes may require that
+=== you modify your configuration files, dialplan or (in
+=== some cases) source code if you have your own Asterisk
+=== modules or patches. These files also includes advance
+=== notice of any functionality that has been marked as
+=== 'deprecated' and may be removed in a future release,
+=== along with the suggested replacement functionality.
 ===
 === UPGRADE-1.2.txt -- Upgrade info for 1.0 to 1.2
 === UPGRADE-1.4.txt -- Upgrade info for 1.2 to 1.4
-=== UPGRADE.txt     -- Upgrade info for 1.4 to 1.6
+===
 =========================================================
 
 AEL:

UPGRADE.txt

@@ -1,10 +1,21 @@
 ===========================================================
+===
 === Information for upgrading between Asterisk 1.6 versions
 ===
+=== These files document all the changes that MUST be taken
+=== into account when upgrading between the Asterisk
+=== versions listed below. These changes may require that
+=== you modify your configuration files, dialplan or (in
+=== some cases) source code if you have your own Asterisk
+=== modules or patches. These files also includes advance
+=== notice of any functionality that has been marked as
+=== 'deprecated' and may be removed in a future release,
+=== along with the suggested replacement functionality.
 ===
 === UPGRADE-1.2.txt -- Upgrade info for 1.0 to 1.2
 === UPGRADE-1.4.txt -- Upgrade info for 1.2 to 1.4
 === UPGRADE-1.6.txt -- Upgrade info for 1.4 to 1.6
+===
 ===========================================================
 
 From 1.6.0.1 to 1.6.1: