smite-nyx-sys: document Nyx FFI bindings

[psg-19]

Added crate level docs for smite-nyx-sys and documented the exported Nyx agent FFI functions

[morehouse]

Suggested change

	//! injects a new input and collects coverage. And all this without restarting the
	//! target process.
	//! injects a new input and collects coverage without restarting the target
	//! process.

[morehouse]

Actually I think it does? max_size determines the size of the payload buffer, which will naturally be the largest input that can ever be returned in data.

Suggested change

	/// `data` must be large enough for the full payload; the C agent does not
	/// clamp the copy to `max_size`. Pass the size returned by [`nyx_init`].
	/// `max_size` is the maximum number of bytes that can be written to `data`.

[morehouse]

Suggested change

	/// Initializes the Nyx agent and returns the maximum fuzz input size
	/// (in bytes) supported by the host.
	/// Initializes the Nyx agent and returns the maximum fuzz input size
	/// (in bytes) supported by the host. Also sets `__AFL_SHM_ID` to the
	/// allocated shared memory ID and sets `AFL_MAP_SIZE` to the size of
	/// the shared memory region.

[morehouse]

Suggested change

	/// Skips the current test case and resets the coverage bitmap and restores
	/// the VM to the snapshot state.
	/// After this call, execution resumes from the snapshot point inside
	/// [`nyx_get_fuzz_input`].
	/// Skips the current test case, resets the coverage bitmap, and restores the
	/// VM to the snapshot state. After this call, execution resumes from the
	/// snapshot point inside [`nyx_get_fuzz_input`].

[morehouse]

Suggested change

	/// state.
	/// After this call the execution resumes from the snapshot point inside
	/// [`nyx_get_fuzz_input`].
	/// state. After this call the execution resumes from the snapshot point
	/// inside [`nyx_get_fuzz_input`].