emacs-28 b9ac8c29ae: Improve terminal-live-p docstring

[Robert Pluim]

branch: emacs-28
commit b9ac8c29aec90b31b044137e1e056daacd8fa1f2
Author: Robert Pluim <rpluim@gmail.com>
Commit: Robert Pluim <rpluim@gmail.com>

    Improve terminal-live-p docstring
    
    * src/terminal.c (Fterminal_live_p): Explain what happens when the
    argument is nil.
---
 src/terminal.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/terminal.c b/src/terminal.c
index 3674eccdbb..39ba3925b7 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -421,7 +421,8 @@ The terminal device is represented by its integer 
identifier.  */)
 
 DEFUN ("terminal-live-p", Fterminal_live_p, Sterminal_live_p, 1, 1, 0,
        doc: /* Return non-nil if OBJECT is a terminal which has not been 
deleted.
-Value is nil if OBJECT is not a live display terminal.
+Value is nil if OBJECT is not a live display terminal.  Uses the
+terminal of the currently selected frame if OBJECT is nil.
 If object is a live display terminal, the return value indicates what
 sort of output terminal it uses.  See the documentation of `framep' for
 possible return values.  */)