Rollup merge of #136019 - scottmcm:alias-unchecked-div, r=Mark-Simulacrum

Add an `unchecked_div` alias to the `Div<NonZero<_>>` impls

Inspired by rust-lang/libs-team#526, if people are looking for `unchecked_div`, point them to `u32: Div<NonZero<u32>>` and friends which do no runtime checks -- and are safe! -- rather than today's behaviour of [the intrinsic being the top result](https://doc.rust-lang.org/std/?search=unchecked_div).

![image](https://github.com/user-attachments/assets/cf2a3c06-4876-49c1-8e33-64cd431c772a)

Author: jhpratt

library/core/src/num/nonzero.rs

@@ -1185,8 +1185,12 @@ macro_rules! nonzero_integer_signedness_dependent_impls {
         impl Div<NonZero<$Int>> for $Int {
             type Output = $Int;
 
+            /// Same as `self / other.get()`, but because `other` is a `NonZero<_>`,
+            /// there's never a runtime check for division-by-zero.
+            ///
             /// This operation rounds towards zero, truncating any fractional
             /// part of the exact result, and cannot panic.
+            #[doc(alias = "unchecked_div")]
             #[inline]
             fn div(self, other: NonZero<$Int>) -> $Int {
                 // SAFETY: Division by zero is checked because `other` is non-zero,
@@ -1197,6 +1201,9 @@ macro_rules! nonzero_integer_signedness_dependent_impls {
 
         #[stable(feature = "nonzero_div_assign", since = "1.79.0")]
         impl DivAssign<NonZero<$Int>> for $Int {
+            /// Same as `self /= other.get()`, but because `other` is a `NonZero<_>`,
+            /// there's never a runtime check for division-by-zero.
+            ///
             /// This operation rounds towards zero, truncating any fractional
             /// part of the exact result, and cannot panic.
             #[inline]