doc: improve 'rm -f' description

* doc/coreutils.texi (rm invocation): Mention that the -f option also
silences the message for missing operands, which is useful in scripts
e.g., for "rm -f $file_list" when $file_list is empty.
* src/rm.c (usage):  Likewise.
Reported by Jérémy Magrin in http://bugs.gnu.org/10819

1 files changed, 1 insertions, 1 deletions

diff --git a/src/rm.c b/src/rm.c
index db525d02c..02809f214 100644
--- a/src/rm.c
+++ b/src/rm.c
@@ -135,7 +135,7 @@ usage (int status)
       fputs (_("\
 Remove (unlink) the FILE(s).\n\
 \n\
-  -f, --force           ignore nonexistent files, never prompt\n\
+  -f, --force           ignore nonexistent files and arguments, never prompt\n\
   -i                    prompt before every removal\n\
 "), stdout);
       fputs (_("\