C# custom Node class dynamic creation issue

**Your Godot version:** V3.2.3.stable.mono.official

**Issue description:**
I was need to instanciate my custom node class dymanically using C#. On this page (https://docs.godotengine.org/en/latest/getting_started/step_by_step/scripting_continued.html) we have "Creating nodes" section that messed things up a little bit. So like it was shown here i just tried to create my class with constructor and attach it to scene tree. Here i got two issues:

1. After creating node dynamically i belive you should set it's owner like it's shown here https://github.com/godotengine/godot/issues/12456

2. If you create node with class constructor is does not work like expected in editor. You have no **exported fields**, also editor says node has no script attached. The right way to create instance of **_custom_** class should be loading it with _Godot.GD.Load()_ function, cast resourse to _Godot.CSharpScript_ and then call _.New()_ method on it:
```
using Godot;

CSharpScript scr = (CSharpScript)GD.Load("res://src/YourClass.cs");
YourClass inst = (YourClass)scr.New();
this.AddChild(inst);
inst.Owner = this;
```

I think this things have to be put in documentation for C# in this section https://docs.godotengine.org/en/latest/getting_started/scripting/c_sharp/c_sharp_differences.html

**URL to the documentation page (if already existing):**