add almost empty CHANGELOG

Signed-off-by: Federico Vaga <federico.vaga@cern.ch>

CHANGELOG.rst

+..
+  SPDX-License-Identifier: CC-BY-SA-4.0
+
+  SPDX-FileCopyrightText: 2019 CERN
+
+==========
+Change Log
+==========
+
+[0.0.0] - 2019-10-21
+====================
+For the time being it does not exists a proper versioning schema for
+general-cores, but today is when we start to thing about it to be able
+to release RPM files for general-cores drivers.