Add meta-openharmony content to the existing RTD docs

Signed-off-by: NawabAhmad <nawab.ahmad.reshi@huawei.com>

docs/yocto-build-system/oniro-build-arch.rst

@@ -7,6 +7,20 @@
 |main_project_name| Build Architecture
 ######################################
 
+Oniro build architecture is composed of multifaceted, independent, modular, and
+reusable building blocks. In order to build OpenHarmony based images and its 
+components, meta-openharmony component serves as one of the major building blocks.
+In context of OpenHarmony, the OS essentially builds upon various components and 
+respective functionalities, and in terms of functionality, the  meta-openharmony 
+component principally helps to desolate the barrier of hardware boundaries, thus
+inevitably transcending the classical OS dichotomy. 
+
+Architecturally, the `meta-openharmony` is a bitbake layer that contains recipes
+for building OpenHarmony images and components. The meta-openharmony includes a 
+number of different repo manifest files, which you can use to fetch all repositories 
+needed for building OpenHarmony. To have a successful build image, ensure that the 
+undelying dependencies and the build procedure is followed in chronological order. 
+
 ``Oniro Project`` architecture is documented using `c4 model <https://c4model.com/>`_.
 
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