docs: rust: Add error handling sections

Add error handling sections to the documentation and use it
to link to the existing code documentation. This will allow
to extend that documentation, use intra-doc links and test
the examples.

Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/rust-for-linux/CANiq72keOdXy0LFKk9SzYWwSjiD710v=hQO4xi+5E4xNALa6cA@mail.gmail.com/


Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Link: https://lore.kernel.org/r/20250115062552.1970768-1-dirk.behme@de.bosch.com


[ Slightly tweaked wording. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>