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>
Link: Rust-for-Linux#1139
Signed-off-by: Alban Kurti <kurti@invicto.ai>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250206-printing_fix-v3-5-a85273b501ae@invicto.ai
[ Replaced Closes with Link since it fixes part of the issue. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: albankurti

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);
 //!     }
 //! }
 //!