[Docs] Update direct connection to directlist in reference.rst

[AlexandreSinger]

See #3746 for context.

[AmirhosseinPoolad]

I did some more searching, apparently OpenFPGA's version of libarchfpga uses <direct_connection>:
https://github.com/lnis-uofu/OpenFPGA/blob/26fef270511e8ef5d8d2a42d99fc595e5bff9ae5/libs/libarchopenfpga/src/read_xml_routing_circuit.cpp#L235

ArchDirect read_xml_direct_circuit(pugi::xml_node& Node,
                                   const pugiutil::loc_data& loc_data,
                                   const CircuitLibrary& circuit_lib) {
  ArchDirect arch_direct;

  /* Parse direct list, this is optional. May not be used */
  pugi::xml_node xml_directs = get_single_child(
    Node, "direct_connection", loc_data, pugiutil::ReqOpt::OPTIONAL);
  /* Not found, we can return */
  if (!xml_directs) {
    return arch_direct;
  }

  /* Iterate over the children under this node,
   * each child should be named after switch
   */
  for (pugi::xml_node xml_direct : xml_directs.children()) {
    /* Error out if the XML child has an invalid name! */
    if (xml_direct.name() != std::string("direct")) {
      bad_tag(xml_direct, loc_data, xml_directs, {"direct"});
    }

VPR would completely ignore this tag. It wouldn't error out, it would just ignore it. I think the idea is that you would have for VPR and <direct_connection> for the OpenFPGA side.

[AlexandreSinger]

I think the idea is that you would have for VPR and <direct_connection> for the OpenFPGA side.

Ah I see. I think it is a bit confusing to have this example in general then lol.

Lets bring this up during the VTR meeting. We can show the current documentation and discuss what to change it to.