Stop keeping 3 copies of the lispref menu structure for no reason

Stop keeping 3 copies of the lispref menu structure for no reason

vol1.texi and vol2.texi are only used to generate TeX output, and this
constructs its own table of contents and does not use the @menu stuff.

* vol1.texi, vol2.texi: No need to keep menus in these files.
* elisp.texi, anti.texi: Comments.