message: doc(c-api) Add another possible Rust pattern
diff: @@ -103,5 +103,6 @@ transfered anywhere (see [the Ownerships Section][#ownerships]).
  `const *T` translates to Rust as `&T`, it's a reference.
  Note: It could translate to `Option<NonNull<T>>` and then we could
  -call `x?.as_ref()` to get a `&T`. Whether we should use this pattern
  -in all the codebase is still under discussion.
  +call `x?.as_ref()` to get a `&T`. It could also translate to
  +`Option<&T>`. Whether we should use such patterns in all the codebase
  +is still under discussion.
  