rust: workqueue: add missing newline to pr_info! examples

The documentation examples in rust/kernel/workqueue.rs use pr_info!
calls that lack a trailing newline. To maintain consistency with
kernel logging practices, this patch adds the newline to all
affected examples.

Fixes: 15b286d ("rust: workqueue: add examples")
Reported-by: Miguel Ojeda <ojeda@kernel.org>
Closes: Rust-for-Linux#1139
Signed-off-by: Alban Kurti <kurti@invicto.ai>

rust/kernel/workqueue.rs

@@ -60,7 +60,7 @@
 //!     type Pointer = Arc<MyStruct>;
 //!
 //!     fn run(this: Arc<MyStruct>) {
-//!         pr_info!("The value is: {}", this.value);
+//!         pr_info!("The value is: {}\n", this.value);
 //!     }
 //! }
 //!
@@ -108,15 +108,15 @@
 //!     type Pointer = Arc<MyStruct>;
 //!
 //!     fn run(this: Arc<MyStruct>) {
-//!         pr_info!("The value is: {}", this.value_1);
+//!         pr_info!("The value is: {}\n", this.value_1);
 //!     }
 //! }
 //!
 //! impl WorkItem<2> for MyStruct {
 //!     type Pointer = Arc<MyStruct>;
 //!
 //!     fn run(this: Arc<MyStruct>) {
-//!         pr_info!("The second value is: {}", this.value_2);
+//!         pr_info!("The second value is: {}\n", this.value_2);
 //!     }
 //! }
 //!