Use just DOC instead of DOC-nn.mm.

Use just DOC instead of DOC-nn.mm.
* lisp/loadup.el: Just use unversioned DOC.
* Makefile.in (install-doc): DOC file is not version specific any more.
* .bzrignore: Don't ignore DOC-* any more.
* admin/quick-install-emacs: Don't prune DOC-* files a any more.
* doc/lispref/loading.texi (Autoload):
* doc/lispref/help.texi (Documentation Basics, Accessing Documentation)
(Accessing Documentation, Accessing Documentation): DOC-* is now DOC.
* etc/.gitignore: Don't ignore DOC-* any more.
* lib-src/makefile.w32-in ($(DOC)): Use DOC rather than DOC-X.
* msdos/sed1x.inp: Don't rewrite DOC any more.
* nt/makefile.w32-in (clean, top-distclean): DOC-X doesn't exist any more.
* src/Makefile.in (bootstrap-clean): DOC-* doesn't exist any more.
* src/makefile.w32-in (DOC): Use just "DOC".