fix documentation for option-set! syntaxen

fix documentation for option-set! syntaxen

* doc/ref/api-evaluation.texi (Scheme Read): Note that read-set! is
  syntax.
  (Scheme Write): Likewise for print-set!.

* doc/ref/api-io.texi (Writing): Remove reference to
  print-options-interface.

* doc/ref/repl-modules.texi (Readline Options): Update, and add entries
  for readline-options, readline-set! et al.