Outdated details on Configuration page on hls4ml site

On [the top level conguration](https://fastmachinelearning.org/hls4ml/api/configuration.html#top-level-configuration) section of the Configuration page, IOType options presented are `io_parallel` and `io_serial`, which I think is deprecated. Got thrown off a couple times; perhaps it can be fixed? The Configuration page is useful overall otherwise.

Many thanks in advance