instanceOf(CustomClass) not rendered correctly in docs

[nicolaslohrer]

Hey there,

thanks for the useful tool!

Using it, I came across a minor issue with custom class propType declarations. I've defined this in a component:

static propTypes = {
  notifications: PropTypes.instanceOf(Immutable.List).isRequired
};

In the generated docs.md the type is displayed as „instanceOf“, which is not particularly useful.

Regards,
Nicolas