rust: types: add examples for the Either type

We aim to have examples in all Rust types, thus add basic ones for the
`Either` type.

Suggested-by: Miguel Ojeda <[email protected]>
Signed-off-by: Nell Shamrell-Harrington <[email protected]>
Tested-by: Dirk Behme <[email protected]>
Reviewed-by: Trevor Gross <[email protected]>
Reviewed-by: Alice Ryhl <[email protected]>
Link: https://rust-for-linux.zulipchat.com/#narrow/stream/291565/topic/x/near/467478085
Link: https://lore.kernel.org/r/[email protected]
[ Reworded slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <[email protected]>

Author: Nell Shamrell-Harrington

rust/kernel/types.rs

@@ -461,6 +461,15 @@ impl<T: AlwaysRefCounted> Drop for ARef<T> {
 }
 
 /// A sum type that always holds either a value of type `L` or `R`.
+///
+/// # Examples
+///
+/// ```
+/// use kernel::types::Either;
+///
+/// let left_value: Either<i32, &str> = Either::Left(7);
+/// let right_value: Either<i32, &str> = Either::Right("right value");
+/// ```
 pub enum Either<L, R> {
     /// Constructs an instance of [`Either`] containing a value of type `L`.
     Left(L),