(Backup, Version Control, VC Concepts)

(Backup, Version Control, VC Concepts)
(Types of Log File, Advanced C-x v v, Log Buffer, Old Versions)
(Registering, VC Status, VC Undo, Multi-User Branching)
(Comparing Files): Replace inforef to emacs-xtra by conditional xref's,
depending on @iftex/@ifnottex.
(Secondary VC Commands) [ifnottex]: Add menu entries for vc-xtra.texi
subsections.
(VC Undo) [ifnottex]: @include vc1-xtra.texi and @lowersections it.
(Multi-User Branching) [ifnottex]: @include vc2-xtra.texi.
(Reverting) [ifnottex]: @include arevert-xtra.texi.
(Files) [ifnottex]: Add menu entry for Autorevert.