docs: Add OpenHarmony subsection to Supported Technologies section

Signed-off-by: Esben Haabendal <esben.haabendal@huawei.com>

docs/definitions.rst

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

docs/supported-technologies/openharmony-image.rst

+.. SPDX-FileCopyrightText: Huawei Inc.
+..
+.. SPDX-License-Identifier: CC-BY-4.0
+
+.. include:: ../definitions.rst
+
+OpenHarmony Image
+#################
+
+Oniro Project can include OpenHarmony compatibility in the predefined images by
+enabling `openharmony` distro feature and adding it to the images.
+
+See :ref:`Building with OpenHarmony compatibility <Building with OpenHarmony>` in
+Quick Build instructions for details on how to do this.

docs/supported-technologies/openharmony-sdk.rst

+../../recipes-openharmony/sdk/README.rst
\ No newline at end of file

docs/supported-technologies/openharmony.rst

+.. SPDX-FileCopyrightText: Huawei Inc.
+..
+.. SPDX-License-Identifier: CC-BY-4.0
+
+.. include:: ../definitions.rst
+
+OpenHarmony
+###########
+
+OpenHarmony is an open-source project incubated and operated by the OpenAtom
+Foundation. It is an open-source operating system with a framework and platform
+applicable to smart devices in all scenarios of a fully-connected world. It aims
+to promote the development of the Internet of Everything (IoE).
+
+OpenHarmony project provides a number of resources, including a Platform
+Compatibility Specification (PCS), a test suite (XTS) for verification of
+products and distributions following the PCS, and a complete reference
+implementation with support for several development boards.
+
+For more details on OpenHarmony project, `Click <https://gitee.com/openharmony>`__.
+
+|main_project_name| provides a number of different Yocto recipes related to
+OpenHarmony.
+
+``openharmony-standard``
+  builds OpenHarmony components from the OpenHarmony projects reference
+  implementation, for use in Oniro and other Yocto based projects.
+
+``oniro-openharmony-toolchain``
+  builds an LLVM toolchain for use with the OpenHarmony reference implementation
+  as a replacement for the default prebuilt toolchain.
+
+``oniro-openharmony-bundle``
+  is similar to the toolchain built with ``oniro-openharmony-toolchain``, but
+  with the addition of selected open-source 3rd party components, which replaces
+  the default versions of those same components provided in the OpenHarmony
+  reference implementation.
+
+``openharmony-standard-image``
+  builds a demo image, integrating the ``openharmony-standard`` output into a
+  bootable demo.
+
+.. toctree::
+   :maxdepth: 1
+
+   openharmony-image
+   openharmony-sdk