rust: pin-init: docs: link Zeroable::zeroed and pin_init::zeroed in documentation

Modify the comments in the `pin_init::zeroed` and `Zeroable::zeroed`
functions to cross-reference each other and make developers aware of both
options.

This also adapts the example code in `Zeroable::zeroed` doc comments to use
that function.

Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/rust-for-linux/CANiq72kdCAyRUmXFcqQfkHpk1miG8Gagsn0_5U8p4WpKxv9d_g@mail.gmail.com/
Signed-off-by: Nicolás Antinori <nico.antinori.7@gmail.com>
[ Fix link. - Gary ]
Signed-off-by: Gary Guo <gary@garyguo.net>

rust/pin-init/src/lib.rs

@@ -1539,10 +1539,13 @@ fn init_zeroed() -> impl Init<Self>
     /// Whenever a type implements [`Zeroable`], this function should be preferred over
     /// [`core::mem::zeroed()`] or using `MaybeUninit<T>::zeroed().assume_init()`.
     ///
+    /// As const traits are not yet stable, [`pin_init::zeroed()`] can be used instead
+    /// when initialization is required in a `const` context.
+    ///
     /// # Examples
     ///
     /// ```
-    /// use pin_init::{Zeroable, zeroed};
+    /// use pin_init::Zeroable;
     ///
     /// #[derive(Zeroable)]
     /// struct Point {
@@ -1550,7 +1553,7 @@ fn init_zeroed() -> impl Init<Self>
     ///     y: u32,
     /// }
     ///
-    /// let point: Point = zeroed();
+    /// let point: Point = Zeroable::zeroed();
     /// assert_eq!(point.x, 0);
     /// assert_eq!(point.y, 0);
     /// ```
@@ -1582,6 +1585,9 @@ pub fn init_zeroed<T: Zeroable>() -> impl Init<T> {
 /// Whenever a type implements [`Zeroable`], this function should be preferred over
 /// [`core::mem::zeroed()`] or using `MaybeUninit<T>::zeroed().assume_init()`.
 ///
+/// While const traits remain unstable, this function serves as the `const` version of
+/// [`Zeroable::zeroed()`].
+///
 /// # Examples
 ///
 /// ```