(Types of Log File): Change logs are older than version control.

(Types of Log File): Change logs are older than version control.
(VCS Concepts): Simplify and rearrange.
(Version Control Systems): Make it clear that Linux is only the kernel.
(VC Mode Line): Shorten reference to menu item.
(Basic VC Editing): Clarify VC fileset.  Shorten and simplify.
(VC Directory Mode): Minor cleanup.
Unchanged files are hidden, not omitted.
(VC Directory Commands): Shorten and simplify.
(Change Log Commands): New node, split from Change Logs.
(VC Directory Buffer): New node, split from VC Directory Mode.