Add explanatory note

src/main.rs

@@ -1,5 +1,5 @@
 #[allow(non_camel_case_types, non_snake_case, dead_code)]
-mod ffi;
+mod ffi; //generated with `bindgen vendor/most-5.1.0/src/most.h -o src/ffi.rs`
 
 fn main() {
     println!("Printing most usage:");