Add 2.0.0 release docs

This MR requires oniro!372 (merged). While this is not merged, CI will fail.

releases/2.0/2.0.0/index.rst

+.. SPDX-FileCopyrightText: Huawei Inc.
+..
+.. SPDX-License-Identifier: CC-BY-4.0
+
+.. include:: ../../../definitions.rst
+
+2.0.0
+#####
+
+**Release timeframe**: 2022-03-07 .. 2022-11-22
+
+.. toctree::
+   :maxdepth: 1
+   
+   release_notes
+   requirements
+   ip_compliance_note