add doc to a bit more

src/hzclient.rs

@@ -1,3 +1,4 @@
+//! Hazelnut C++ client bindings.
 use std::ffi;
 
 pub(crate) mod sys {
@@ -6,8 +7,13 @@ pub(crate) mod sys {
     #[repr(u32)]
     #[allow(unused)] // it IS used, just not by Rust
     pub enum ResultCode {
+        /// The frame has not been changed. (This is implemented internally by comparing the frame serial; if it has changed then the frame has too)
         Unchanged,
+
+        /// The frame has been changed.
         Changed,
+
+        /// A failure occured during the tick.
         Fail,
     }