fix doc comment

src/bin/client.rs

@@ -292,7 +292,7 @@ impl Conversation<Active> {
     }
 }
 
-/// Attempt to read some portion of the size of the reast of the header from the stream.
+/// Attempt to read some portion of the header size from the stream.
 /// The number of bytes written is returned in the Ok case.
 /// The caller must read any remaining bytes less than 4.
 // N.B.: This must be written cancellation safe!