Update docs with alternative route config about ex-navigation

[grabbou]

@chirag04 yup, all I am saying is that for me it's just easier to work on the app when the route configuration is in one place (in this case, a file where createRouter is called) instead of being defined in each scene file separately, as in the example demonstrated by you.

If both ways are supported, they should be IMO documented, otherwise it's not clear why they are there :)

[chirag04]

@brentvatne actually gave me an example y you would want to use config. I can't find it and not sure y would you use config. If we are to document this I think we should document the usecase also otherwise it would confuse more people.

@grabbou you can have navigationBar with title on the HomeScene.

function HomeScene(props) {
}
HomeScene.route = {
    navigationBar: {
       title: 'Home',
    }
};

[brentvatne]

I don't like how we're using a private api (makeRoute) here. If this is really important, we should make it possible to pass in component alongside config, where the component passed in gets wrapped by makeRoute internally -- closing this issue but a PR would be welcome!