Update file names

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@120733 65c4cc65-6c06-0410-ace0-fbb531ad65f3

UPGRADE-1.2.txt

@@ -3,8 +3,7 @@
 ===
 ===
 === 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
+=== UPGRADE.txt -- Upgrade info for 1.2 to 1.4
 =========================================================
 
 Compiling: