add Tracker tie syntax to demo notebook

[djcunningham0]

The demo notebook does not show how to implement ties in the Tracker object, despite what this comment says. (The functionality exists, just need to demonstrate it in the notebook.)

multielo/demo.ipynb

Line 1082 in 440f792

"As of version 0.3.0, this Elo implementation can handle ties. The syntax to annotate ties in the `MultiElo` and `Tracker` objects is shown below.\n",

[Azzoh]

I would love to know how to implement ties in the Tracker object, it would be very usefull for me !