So how do I add a docking system to a gate?
You can't. If you disable the marshaller, nothing will take its place in the current GSX version. The point of that feature, is to disable the marshaller if your 3rd party scenery ALREADY comes with its own docking systems or marshallers, to get rid of duplicates, but you can't add a docking system on a scenery that doesn't have them. We might eventually add a docking system editor, but it's not there right now.
The release notes were meant to say that, if you set the option to disable/enable a marshaller on some of OUR sceneries that have a customization which adds docking systems (which is not the same customization of what you can do with the editor that comes with GSX), the docking system disappeared, regardless if the option was set as True or False.
This was a bug of course, so we fixed it and now it correctly disables the docking system only if the "Disable" option is set to True, and we also changed the customization dialog to be a bit more clear that the option, IF set to Disable, will disable every parking assistance on the scenery, either a Marshaller or a Docking system.