Rollup merge of #31535 - Ketsuban:more-detail-in-wrapping-shift-documentation, r...

Rollup merge of #31535 - Ketsuban:more-detail-in-wrapping-shift-documentation, r=steveklabnik

`wrapping_shl` and `wrapping_shr` are easy to mistake for rotations, when in fact they work somewhat differently. The documentation currently available is a little sparse and easy to misinterpret, so I've added a warning to anyone who bumps into them that the equivalent rotate methods may actually be what they're looking for.

If it's deemed useful to add a symmetrical mention to the documentation for the `rotate_left` and `rotate_right` methods, I can certainly have a go at that, but my gut feeling is that people likely to want a rotate will already know about the wrapping-arithmetic methods, for example from writing CPU simulators.