Update changes.txt to cover Unicode and LuaTeX changes
tree02145db690558a5916f8b82a0589b713f793b9fd
drwxr-xr-x - base
-rw-r--r-- 832 build-config.lua
-rw-r--r-- 2221 build.lua
drwxr-xr-x - doc
drwxr-xr-x - required
drwxr-xr-x - scripts
drwxr-xr-x - support
drwxr-xr-x - validate