Rollup merge of #59529 - DevQps:improve-rem-docs, r=cuviper
Rollup merge of #59529 - DevQps:improve-rem-docs, r=cuviper

Added documentation on the remainder (Rem) operator for floating points.

# Description

As has been explained in #57738 the remainder operator on floating points is not clear.
This PR requests adds some information on how the `Rem` / remainder operator on floating points works.

Note also that this description is for both `Rem<f32> for f32` and `Rem<f64> for f64` implementations.

Ps. I wasn't really sure on how to formulate things. So please suggest changes if you have better idea's!

closes #57738

aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust