bug#29551: 24.5; doc string of `bookmark-alist'

[Drew Adams]

A bookmark is more than a name.

The first line of the doc string says this:

  Association list of bookmarks and their records.

That's wrong, or at best misleading.  Each entry in the alist is a
_bookmark_.  That is, each entry is a bookmark "record", whose car
is the bookmark name, and whose cdr is the associated bookmark data.

The doc should say something like this:

"Association list of bookmark names and bookmark data."
or
"Association list of bookmark records." (and then say what a record is)

In GNU Emacs 24.5.1 (i686-pc-mingw32)
 of 2015-04-11 on LEG570
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/usr --host=i686-pc-mingw32'