License: Improve license statement.

The README mentions only the MIT license but in fact part of `jq`
is under ICU license and the documentation is under CC.

Also jq.spec claimed that it is licensed under BSD.

jq.spec

@@ -6,7 +6,7 @@ Version: %{myver}
 Release: %{myrel}%{?dist}
 Source0: jq-%{myver}.tar.gz
 URL: https://jqlang.github.io/jq
-License: BSD
+License: MIT AND ICU AND CC-BY-3.0
 AutoReqProv: no
 #BuildPrereq: autoconf, libtool, automake, flex, bison, python