DOC: stats: resampling and Monte Carlo methods tutorials

[mdhaber]

Notebooks corresponding with scipy/scipy#16699 as discussed in scipy/scipy#16699 (comment).
@mckib2

[mdhaber]

@rgommers Can you give @mckib2 and me access here? We're going to add a tutorial for MILP, too.

[rgommers]

Ah, I see that write access to this repo was missing from the Maintainers team - added now.

[mckib2]

Thanks @rgommers!

This has reviewed by multiple people (including myself) over the course of several months, so this is ready to go straight in. Thanks @mdhaber!