Update docs for select-window and buffer-list-update-hook.

Update docs for select-window and buffer-list-update-hook.

* buffer.c (Vbuffer_list_update_hook): Doc-string fix.
* window.c (Fselect_window): Explain NORECORD and
`buffer-list-update-hook' in doc-string.
* buffers.texi (The Buffer List): Rename node to Buffer List.
Describe `buffer-list-update-hook'.
* elisp.texi (Top): "The Buffer List" renamed to "Buffer List".
Add node for Window Dividers.
* hooks.texi (Standard Hooks): Add reference to
`buffer-list-update-hook'.
* windows.texi (Selecting Windows): Update description of
`select-window'.