Mention left-hand-rule for naming

[MarcoGorelli]

Setting the name in the result of a polars plugin has no effect, because Polars just follows the left-hand-rule (or whichever alias the user passes)

is this mentioned in the tutorial? if not, it should be mentioned somewhere

[j824h]

It is mentioned here, which I found helpful. It does seem that the information, not specific to struct, could be better positioned.