doc: Add some more RCU list patterns in the kernel

- Add more information about RCU list patterns taking examples
from audit subsystem in the linux kernel.

- Keep the current audit examples, even though the kernel has changed.

- Modify inline text for better passage quality.

- Fix typo in code-blocks and improve code comments.

- Add text formatting (italics, bold and code) for better emphasis.

Patch originally submitted at
https://lore.kernel.org/patchwork/patch/1082804/

Co-developed-by: Amol Grover <[email protected]>
Signed-off-by: Amol Grover <[email protected]>
Signed-off-by: Joel Fernandes (Google) <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

Author: joelagnel