Add example using own data sets

[grd349]

@ojhall94 has a nice example of analysing 16 Cyg A where he uses his own data that he plus into lightcurve and then run PBjam star. We should add this example to the docs somewhere.

It's probably more about interacting with lightkurve than anything else but probably an issue users will care about.

We should add a few more orders to the example and we should fix the problem #204 to make it look nicer.

[nielsenmb]

Is there a link to this notebook? It sounds like that's what happens when you give pbjam.session a numpy array or file name instead of a lightkurve object.

This is of course not possible if we want the tutorial to show the pbjam.star case, but for pbjam.session it's trivial.

[grd349]

@ojhall94 - do you have the 16 Cyg notebook? We'll make it pretty if you can shoot it across.