docs: defnitions value updated

Updated the defninition Project name  value

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

docs/definitions.rst

 .. SPDX-FileCopyrightText: Huawei Inc.
 ..
 .. SPDX-License-Identifier: CC-BY-4.0
-.. |main_project_name| replace:: All Scenarios OS
+.. |main_project_name| replace:: Oniro Project