added some comments for mount-chroot()

git-svn-id: http://trac.vinelinux.org/repos/projects/vbootstrap/trunk@851 ec354946-7b23-47d6-9f5a-488ba84defc7

vbuilder.sh.in

@@ -416,10 +416,11 @@ apt-get-update(){
 
 ## mount-chroot {|--umount} [file system|name]
 ## support file systems: /home /tmp /sys /proc /dev/shm /dev/pts /dev
-## support name: vfs chache_dir
+## support name: vfs archives_dir
 ## NOTE: /tmp needs for applications which use X
 ##       vfs is virtual file systems
-##       archives_dir is ${EXTERNAL_ARCHIVES_DIR} to ${ARCHIVES_DIR}
+##       archives_dir uses to mount ${EXTERNAL_ARCHIVES_DIR} to ${ARCHIVES_DIR}
+##       unionfs_dir covers ${BUILD_ROOT} with unionfs
 mount-chroot(){
     if [ "$1" = "--umount" ]; then
 	mount-chroot-umount $2 || return 1