compat: use tarantool.io URLs for compat options

We plan to provide compat options information via the website. It was
requested by Kirill Yukhin instead of the wiki pages (and I don't mind
it).

NO_DOC=notified the documentation team in
       https://github.com/tarantool/doc/issues/3259
NO_TEST=it's just help messages
NO_CHANGELOG=those compat options were not released yet