Document Emacs 26 behavior of Dired's 'Z' on directories

* doc/emacs/dired.texi (Operating on Files): Document behavior
of 'Z' on directories.

* etc/NEWS: Belatedly announce the new behavior of Dired's 'Z'
on directory names and on .tar.gz archives.

1 files changed, 8 insertions, 2 deletions

diff --git a/doc/emacs/dired.texi b/doc/emacs/dired.texi
index fba9d31406e..9c408e13ae7 100644
--- a/doc/emacs/dired.texi
+++ b/doc/emacs/dired.texi
@@ -768,9 +768,15 @@ suitable guess made using the variables @code{lpr-command} and
 @item Z
 Compress the specified files (@code{dired-do-compress}).  If the file
 appears to be a compressed file already, uncompress it instead.  Each
-marked file is compressed into its own archive.  This uses the
+marked file is compressed into its own archive; this uses the
 @command{gzip} program if it is available, otherwise it uses
-@command{compress}.
+@command{compress}.  On a directory name, this command produces a
+compressed @file{.tar.gz} archive containing all of the directory's
+files, by running the @command{tar} command with output piped to
+@command{gzip}.  To allow decompression of compressed directories,
+typing @kbd{Z} on a @file{.tar.gz} or @file{.tgz} archive file unpacks
+all the files in the archive into a directory whose name is the
+archive name with the extension removed.
 
 @findex dired-do-compress-to
 @kindex c @r{(Dired)}