ps.1: update regarding -D option and -p x/d interaction

The -p option does not imply -x, it is merely a different mode that ps
uses. Remove that statement from the -p option, effectively rolling back
d6ae056e9d.

pstef@ introduced the -D option in 5c0a1c15ff
which also turns ps into a similar mode. List the -D option along with
the others in the first sentence of the second paragraph of the
DESCRIPTION section for completeness and correctness sake.

Pointed out by:		pstef@
Differential Revision:	https://reviews.freebsd.org/D42552

bin/ps/ps.1

@@ -28,7 +28,7 @@
 .\"
 .\"     @(#)ps.1	8.3 (Berkeley) 4/18/94
 .\"
-.Dd October 6, 2023
+.Dd November 11, 2023
 .Dt PS 1
 .Os
 .Sh NAME
@@ -65,7 +65,7 @@ will also display processes that do not have controlling terminals.
 .Pp
 A different set of processes can be selected for display by using any
 combination of the
-.Fl a , G , J , p , T , t ,
+.Fl a , D , G , J , p , T , t ,
 and
 .Fl U
 options.
@@ -238,11 +238,6 @@ So the header texts for multiple keywords can be changed.
 If all keywords have empty header texts, no header line is written.
 .It Fl p
 Display information about processes which match the specified process IDs.
-It implies the use of
-.Fl x .
-When combined with
-.Fl d ,
-all descendent processes are included.
 .It Fl r
 Sort by current CPU usage, instead of the combination of controlling
 terminal and process ID.