Program description

[suntong]

I've glimpsed through the help doc and it seems that there is no way to provide "program description", i.e., what the program is, what it does etc in the output help.

E.g., when you run rsync -h, before showing the usage, it first explains what it does:

rsync is a file transfer program capable of efficient remote update
via a fast differencing algorithm.

Usage: rsync [OPTION]... SRC [SRC]... DEST
  or   rsync [OPTION]... SRC [SRC]... [USER@]HOST:DEST
  or   rsync [OPTION]... SRC [SRC]... [USER@]HOST::DEST

IMHO, this is necessary for every program.

Please consider adding it.