[21.3] find-dired should be named dired-find (like grep-find)

[Jari Aalto+mail.linux]

In GNU Emacs 21.3.1 (i386-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2004-08-03 on raven, modified by Debian

I think it would be consistent with the rest of the function to change
function name:

    find-dired => dired-find

Motivation: There is `grep' and `grep-find'. It is also more intuitive
to call 'dired' + `find' listing, because the results are put to a
dired buffer.

Jari