Add Logo License Info

* Add logo license info

* Add CSS file license info

* Closes: https://booting.oniroproject.org/distro/docs/-/issues/96



Signed-off-by: Gururaj Shetty <gururaj.shetty@huawei.com>

ONIRO.svg.license

+SPDX-FileCopyrightText: Huawei Inc.
+
+SPDX-License-Identifier: CC-BY-4.0

_static/css/custom.css

+/*
+SPDX-FileCopyrightText: Huawei Inc.
+
+SPDX-License-Identifier: CC-BY-4.0
+*/
+
 /* 
 Configuration of logo width in pixels
 */