pages existed only for the dynamic sysctl interfaces. There's probably
more complete and accurate content, better advice, etc, that could be added
here.
Per scottl's suggest, add a small piece of moralizing text regarding the
fact that sysctl names quickly get embedded in system configuration files,
libraries, third party applications, and even books, so renaming and
removing names after they've been published is a tricky issue.
MFC after: 1 month
