rust: error: add C header links

The error codes come from several headers.

Thus, add the other header links.

Signed-off-by: Onur Özkan <work@onurozkan.dev>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
[ Sorted headers. Added line breaks. Reworded commit message. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: onur-ozkan

rust/kernel/error.rs

@@ -2,7 +2,9 @@
 
 //! Kernel errors.
 //!
-//! C header: [`include/uapi/asm-generic/errno-base.h`](srctree/include/uapi/asm-generic/errno-base.h)
+//! C header: [`include/uapi/asm-generic/errno-base.h`](srctree/include/uapi/asm-generic/errno-base.h)\
+//! C header: [`include/uapi/asm-generic/errno.h`](srctree/include/uapi/asm-generic/errno.h)\
+//! C header: [`include/linux/errno.h`](srctree/include/linux/errno.h)
 
 use crate::{
     alloc::{layout::LayoutError, AllocError},