Update package comments

cryptmt.go

@@ -1,10 +1,13 @@
-// CryptMT
+// Package CryptMT - implementation of cryptMTv1 stream cipher
+// (but with mtwist64 as base accum) 
+// https://eprint.iacr.org/2005/165.pdf 
 package cryptmt
 
 // TODO rlm: according to go docs, stream ciphers do not implement the
 // cipher.Block interface at all (thus do not support Encrypt() or
 // Decrypt() .. cipher.StreamReader/StreamWriter() only call
-// XORKeyStream() anyhow.
+// XORKeyStream() anyhow and for my own purposes this is all that is
+// required.
 
 import (
 	"errors"