Tweak Gnus doc re gnus-copy-file

* doc/misc/gnus.texi (Saving Articles):
Document behavior with directory name targets (Bug#27986).
Problem reported by Katsumi Yamaoka in:
http://lists.gnu.org/archive/html/emacs-devel/2017-09/msg00216.html

1 files changed, 3 insertions, 1 deletions

diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index 3e9b48ec65d..b002f5dea7e 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -7759,7 +7759,9 @@ processing of the article is done before it is saved).  For a different
 approach (uudecoding, unsharing) you should use @code{gnus-uu}
 (@pxref{Decoding Articles}).
 
-For the commands listed here, the target is a file.  If you want to
+For the commands listed here, the target is a file.
+A directory name (ending in @samp{/}) causes the target
+to be a file under that directory.  If you want to
 save to a group, see the @kbd{B c} (@code{gnus-summary-copy-article})
 command (@pxref{Mail Group Commands}).