#19411: Clarify that b2a_hex/hexlify returns a bytes object.

Initial patch by Vajrasky Kok.
diff --git a/Modules/binascii.c b/Modules/binascii.c
index 340ec9c..a84badc 100644
--- a/Modules/binascii.c
+++ b/Modules/binascii.c
@@ -1129,7 +1129,8 @@
 PyDoc_STRVAR(doc_hexlify,
 "b2a_hex(data) -> s; Hexadecimal representation of binary data.\n\
 \n\
-This function is also available as \"hexlify()\".");
+The return value is a bytes object.  This function is also\n\
+available as \"hexlify()\".");
 
 
 static int