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: 15b286d1 ("rust: workqueue: add examples")
Reported-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/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>