rust fuzzing - more info for sanitizers

[GrosQuildu]

We can write more about advances sanitizer use-cases for rust fuzzing (https://appsec.guide/docs/fuzzing/rust/):

• instrument only C bindings and not rust code, like in https://maxammann.org/posts/2021/06/sanitize-rust-sys-crate/
• instrument rust std lib as recommended in https://doc.rust-lang.org/beta/unstable-book/compiler-flags/sanitizer.html#instrumentation-of-external-dependencies-and-std
• instrument only parts of Rust code (selected Rust functions or only unsafe code) to better guide the fuzzing