docs: fix typo in example of interleaved-tables (#209)
docs: fix typo in example of interleaved-tables (#209)

Co-authored-by: nownabe <8ffe2137130469c4cbf73e664b1aef35901168fd@users.noreply.github.com>
Co-authored-by: Knut Olav Løite <62634d14bf6dff6edb4b7af974862bb227095f71@gmail.com>
googleapis/ruby-spanner-activerecord,googleapis/ruby-spanner-activerecord