bug#19274: tar-mode.el: allow for adding new archive members

[Eli Zaretskii <eliz@gnu.org>]

> From: Ivan Shmakov <ivan@siamics.net>
> Date: Sat, 06 Dec 2014 20:50:36 +0000
> 
>  >   fgrep -w Tar doc/emacs/*.texi 
> 
> 	Now, it makes me wonder if there should be an @findex tar-mode
> 	along with the @cindices?  (And @findex archive-mode, too.)

What, just to help us search for it?  These functions are never
mentioned in that node.

But I don't mind adding the index entries.

(In general, the best way of doing this search is to take note of the
node you are reading in Info, and then search for the corresponding
@node line.)

> 	Otherwise, does the patch MIMEd look sane?

Yes, with one comment; see below.

> +  The @kbd{I} key adds a new (regular) file to the archive.  The file
> +is initially empty, but can readily be edited using the commands
> +above.  The command inserts the new file on the line above the current
> +one, so that using it on the topmost line of the Tar buffer makes the
> +new file the first one in the archive, and using it on the last line
> +(the one after the line describing the last file) makes it the last
> +one.

Instead of the complicated description of "the last line, which is one
line after the last file's line", I'd simply say "at the end of the
buffer".  This is simpler and much more clear, especially to
non-native speakers who might have problems with long and complex
sentences.

Otherwise, it's fine.  Thanks.  (Don't forget to mark the NEWS entry
with "+++" together with installing this change.)