reword the 'D' dump bit to make it clear that the malloc.out file needs

to exist before exit for malloc to dump stats in it.
tweaks from jmc@
ok otto@,jmc@

src/lib/libc/stdlib/malloc.3

@@ -30,9 +30,9 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: malloc.3,v 1.66 2010/05/18 22:24:55 tedu Exp $
+.\"	$OpenBSD: malloc.3,v 1.67 2010/05/26 07:27:38 thib Exp $
 .\"
-.Dd $Mdocdate: May 18 2010 $
+.Dd $Mdocdate: May 26 2010 $
 .Dt MALLOC 3
 .Os
 .Sh NAME
@@ -223,8 +223,9 @@ rather than when the bogus pointer was used.
 .It Cm D
 .Dq Dump .
 .Fn malloc
-will dump statistics in a file called
-.Pa malloc.out
+will dump statistics to the file 
+.Pa ./malloc.out ,
+if it already exists,
 at exit.
 This option requires the library to have been compiled with -DMALLOC_STATS in
 order to have any effect.