Re: add info about safe-local-variable to describe-variable

[Luc Teirlinck]

_If_ we are going to keep that safe-local-variable trivia in the `C-h v'
output, then at least it should be formulated in a less confusing way:

  This variable is safe to use as a file local variable only if its value
  satisfies the predicate ...

These variables are perfectly safe to use as file local variables in
one's own files.  What is not safe is to blindly accept somebody
else's use of these file local variables.

Also, the present text looks like a warning message: "Beware, this is
a dangerous variable!', whereas variables without safe-local-variable
property are actually considered _more_ dangerous by default.

An improvement would be:

  This variable is considered safe as a file local variable if its
  value satisfies the predicate ...

Deleting "to use" avoids the first confusion.  Replacing "only if" by
"if" avoids the warning aspect.  The "is considered" weakens the
implication that all other values are necessarily dangerous, whereas
usually only some are.

Sincerely,

Luc.