Fix typos

include/librustzcash.h

@@ -12,7 +12,7 @@ extern "C" {
     /// Initializes some parameters for sapling-crypto,
     /// returning a pointer to the parameters. You should
     /// free this when you're done with 
-    /// `librustzcash_init_params()`.
+    /// `librustzcash_free_params()`.
     librustzcash_params* librustzcash_init_params();
 
     /// Frees some parameters that were previously returned

src/rustzcash.rs

@@ -90,7 +90,7 @@ pub extern "system" fn librustzcash_merkle_hash(
     ).into_xy().0.into_repr();
 
     // Should be okay, caller is responsible for ensuring the pointer
-    // is valid.
+    // is a valid pointer to 32 bytes that can be mutated.
     let result = unsafe { &mut *result };
 
     tmp.write_be(&mut result[..]).unwrap();