move read and print options docs to the procedures they parameterize

move read and print options docs to the procedures they parameterize

* doc/ref/api-evaluation.texi (Scheme Read): Fold all reader options
  docs into this section. Undocument read-options-interface.
  (Scheme Write): New section for `write' and `display', and the print
  options. print-enable/print-disable are not documented, as there are
  no boolean print options. print-options-interface is likewise
  undocumented.

* doc/ref/api-options.texi: Remove discussion of options in
  general. Move read options to Scheme Read, and print options to Scheme
  Write.

* doc/ref/api-io.texi (Reading): Link to Scheme Read.
  (Writing): Move write and display to Scheme Write, and link there.

* doc/ref/srfi-modules.texi:
* doc/ref/api-debug.texi:
* doc/ref/api-data.texi: Update xrefs.