Fix description of EncodingRef

Co-authored-by: Daniel Alley <dalley@redhat.com>

src/reader.rs

@@ -56,7 +56,7 @@ enum TagState {
     Exit,
 }
 
-/// A reference to an encoding together with an information of how it was retrieved.
+/// A reference to an encoding together with information about how it was retrieved.
 ///
 /// The state transition diagram:
 ///