don't move cursor after exiting digest

don't move cursor after exiting digest

[jidanni]

C-d runs the command gnus-summary-enter-digest-group

OK, but I always find myself having to do an extra <up> here:
C-d q <up> E

Hmmm, looking at
  q runs the command gnus-summary-exit
    which is an interactive compiled Lisp function in `gnus-sum.el'.
  It is bound to q, Z Z, Z Q, <menu-bar> <Gnus> <Exit> <Exit group>.
  (gnus-summary-exit &optional TEMPORARY LEAVE-HIDDEN)

  Exit reading current newsgroup, and then return to group selection mode.
  `gnus-exit-group-hook' is called with no arguments if that value is non-nil.

OK, but 1) you're not always exiting to group selection mode, but
sometimes just to the *Summary*.

2) Ah, we see these cases are covered,

		;; If this group has disappeared from the summary
		;; buffer, don't skip forwards.
		(not (string= group (gnus-group-group-name))))
      (gnus-group-next-unread-group 1))

But not mine.

OK, most users like doing gnus-group-next-unread-group 1
automatically, but not me...

3) document TEMPORARY LEAVE-HIDDEN