Comments on README file about cvtreemle

[blind-contours]

I have updated the brief explanation of the simulation and the respective "mixture cube". I've increased the nfolds to 5, originally it was smaller for easier testing of the package. I've added a real world example in the vignette and there is a breast cancer example in the tests. I've included discussion of ML via SL3 in the readme and vignette.

[lightning-auriga]

I'll also post related comments under this issue, to keep things organized.

[lightning-auriga]

contributions: the contribution link https://github.com/blind-contours/CVtreeMLE/blob/master/CONTRIBUTING.md does not lead anywhere

[lightning-auriga]

I'll add here the following:

• there's substantial example usage for simulation, both here and in the vignette, but a real world example would be really helpful
• since there's such integration with SL3, a brief discussion of intended use (in text, not code) would probably be warranted, especially because it seems like some of the package's behavioral guarantees really rely on that package