Documentation: Tutorial for parallel repetition for extended nonlocal games

[vprusso]

The existing tutorial on extended nonlocal games found here does not currently cover how one can perform multiple parallel repetitions of a given extended nonlocal game.

It would be nice to cover the idea of what parallel repetitions are in this context and to also show some numerical results that tie into known results in the literature. For example, an example showing that the non-signaling value of the BB84 extended nonlocal game does not obey strong parallel repetition (it fails for n=2 repetitions).