Some remember doc

Some remember doc

* doc/misc/remember.texi (copying): Bump remember mode version.
(Installation): Remove unnecessary chapter.
(Quick Start): No need to explicitly load remember.el.
(Separate Text Files): New section.

* lisp/textmodes/remember.el (remember-data-directory)
(remember-directory-file-name-format, remember-store-in-files)
(remember-notes-initial-major-mode, remember-notes-bury-on-kill)
(remember-notes-save-and-bury-buffer)
(remember-notes--kill-buffer-query): Doc fixes.

* etc/NEWS: Related edit.