Fix broken <cref> tag in PortStatus.cs to PortController

[cjsha]

PortStatus.cs has a <cref> reference to a member PortController of a private class ConfigurePortController which results in a broken link on the docs site because docfx is set to not generate pages for private classes.

Specifically line 15 below:

https://github.com/open-ephys/onix-bonsai-onix1/blob/70a29e51612ff23f440ff808fd44d1b9fb06e3a0/OpenEphys.Onix1/PortStatus.cs#L12-L16

[cjsha]

I set this as the nearest milestone so we can update the docs to point to the latest commit as soon as possible.

[cjsha]

If we want, I can make an exception for portController to render the page. However, if it's not accessible by the user, I agree with what bparks said in #239 about removing the the reference.