chore(121952): remove redundant comments

These were only relevant for the unsafe-containing implementations

Signed-off-by: Petr Portnov <me@progrm-jarvis.ru>

Author: JarvisCraft

library/core/src/num/nonzero.rs

@@ -790,8 +790,6 @@ macro_rules! nonzero_integer_signedness_dependent_impls {
         impl Div<$Ty> for $Int {
             type Output = $Int;
 
-            /// This operation rounds towards zero,
-            /// truncating any fractional part of the exact result, and cannot panic.
             #[inline]
             fn div(self, other: $Ty) -> $Int {
                 // SAFETY: div by zero is checked because `other` is a nonzero,
@@ -802,8 +800,6 @@ macro_rules! nonzero_integer_signedness_dependent_impls {
 
         #[stable(feature = "nonzero_div_assign", since = "CURRENT_RUSTC_VERSION")]
         impl DivAssign<$Ty> for $Int {
-            /// This operation rounds towards zero,
-            /// truncating any fractional part of the exact result, and cannot panic.
             #[inline]
             fn div_assign(&mut self, other: $Ty) {
                 *self = *self / other;