kmac: update the documention for the customisation string maximum length
@@ -42,7 +42,7 @@ Setting this parameter is identical to passing a I<key> to L<EVP_MAC_init(3)>.
=item "custom" (B<OSSL_MAC_PARAM_CUSTOM>) <octet string>
Sets the custom value.
-It is an optional value of at most 127 bytes, and is empty by default.
+It is an optional value of at most 256 bytes, and is empty by default.
=item "size" (B<OSSL_MAC_PARAM_SIZE>) <unsigned integer>
